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£ 1 RE SUPPRESS ION SYMPOS I DM
* REPORT,

24-25 July 1979) „ I

i * I

Prepared By

Directorate of Combat Developments
U&J ■Me Id Artillery School*/

Port Sill, Oklahoma 71503
14 January 1980

TABLE OF CONTENTS

SECTION

PAGE

I. FOREWORD 1-1

II. FIRE SUPPRESSION SYMPOSIUM SCHEDULE II-l

III. FIRST SESSION - PRESENTATIONS III-l

A. Methodology for Quantifying Suppressive Effects III-A-1

of Artillery

B. Suppression in the TRADOC III-B-1

C. Suppression Testing III-C-1

D. Suppression Modeling v/Data from Yom Kippur War III-D-1

E. Suppression of Enemy Air Defense (SEAD) III-E-1

F. Human Behavior in Combat III-F-1

IV. WORK GROUP SUBJECTS AND PARTICIPANTS IV- 1

V. SECOND AND THIRD SESSIONS - WORK GROUPS' RESULTS V-l

A. Group Is Suppression Variables (Effects) V-A-l

B. Group II: Suppression Variables (Causes) V-B-l

C. Group III: Data Base Requirements V-C-l

D. Group IV: Suppression Modeling V-D-l

E. Croup V: Suppreasion/Countersuppresslon Combat and V-E-l

Training Developments

VI. ADDITIONAL MATERIAL - APPENDICES A THRU G VI-1

SECTION Is FOREWORD

On 24 and 25 July 1979 a Fire Suppression Symposium hosted by the
Directorate of Combat Developments (USAFAS) was held at Fort Sill. The
purpose of the symposium was to arrive at a unified approach for studying
the suppressive effects of fires on the modern battlefield.*-^. total of
50 individuals participated in the five work groups with approximately \

40 members from the civilian and military analytical community outside )
of Fort Sill. — * - - — ~ .

^>Tha symposium was divided into three sessions. with the first session
being devoted to presentations by six participants. \ (The sixth presenta¬
tion was made during the evening of the first day.) ^At the conclusion of
the firet session the participants arrived at a consensus definition of
"suppression." It was "Suppression is the process of temporarily degrading
unit or individual combat performance through psychological and physical
means." The symposium members also decided that within the framework of
the definition the focus of the work groups would be on the direct fire
and indirect fire aspects of suppression. Electronic warfare, psychologi¬
cal operations, and obscuration ware considered, but it was decided thut
because of the limited amount of time allotted, the discussion of them
would be deferred.

In the second session participants worked in their five work groups
centering attention on their specific subject area df as shown in the table )
of contents (Section V), The second session terminated group activities J
for the first day of the symposium. Reports on the proceedings of each /
group were collected and reproduced.

9*t the beginning of the third session the participants received a re¬
produced copy of the proceedings of each group's effort up to that point.

In this manner "cross-fertilisation" between groups was effected. sAcain
the participants met in their respective groups, finnllzed their work,
and adjourned to the Combined Arms Room where each work group leader \

presented a summary of hia group's effort, ,.J

In addition, there were other materials submitted, but not presented
at the symposium, fheoe materials are included in Section VI of this
report.^

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SECTION II: FIRE SUPPRESSION SYMPOSIUM

SCHEDULE

Fort Sill, Oklahoma

24 July

0800-0830

Inprocessing

0840-0850

Opening Remarks

MG Jack N. Merritt

CAR, Room 115, Snow Hall

0900-0930

"Methodology for Quantifying
Suppressive Effects of
Artillery"

Mr. Landry, SPC

0930-1000

"Suppression In the TRADOC"

Mr. Roger Willis,

TRASANA

1000-1030

Coffee Break

1030-1100

"Suppression Testing"

Dr. Marlon Bryson, CDEC

1100-1130

"Suppression Modeling
w/Data from Yom Kippur War"

Mr. Paul Kunselman, AMSAA

1130-1200

"SEAD"

LTC Redding, USAF

1200-1330

Lunch

1330-1630

Working Groups

1900-2100

Dinner

"Human Behavior in Combat"

COL Trevor Dupuy

25 July

0800-1000

Working Croups

1000-1030

Coffee Break

1030-1200

Summary of Work Groups

Combined Arms Room,

Room 115, Snow Hall

11-1

SECTION III: FIRST SESSION-PRESENTATIONS

)te. In order to stimulate the thoughts of the participants, six of them were
asked to present the results of their study of suppression. For the
first four speeches only the paper copies of the transparencies used were
provided by the speakers; however, transcripts of the last two speeches
were made available! The titles of the speeches along with the natnes of
the speakers appear below in the order in which they were presented.

"Methodology for Quantifying Suppressive Effects of Artillery" -

Mr. Clifford J. Landry, Director, Land Systems Division, Systems Planning

Corporation.

"Suppression in the TRADOC" - Mr. Roger Willis, Operations Research Analyst,
Chief Phenomenology and Modal Processes Branch (TRASANA) .

"Suppression Testing" - Dr. Marion Bryson, Scientific Advisor, HQ, USACDEC.

"Suppression Modeling w/Data from Yom Kippur War" - Mr. Paul KunBelman,
Physicist with Tactical Operations Office, AMSAA.

"Suppression of Enemy Air Defense (SEAD)" - LTC Kenneth Redding, United
States Air Force Representative at Fort Sill, Oklahoma.

"ruman Behavior in Combat" - COL (Ret) Trevor N. Dupuy, Noted Author,
President, T.N. Dupuy Associates.

A. "Methodology for Quantifying Suppressive Effects of Artillery'
Mr. Clifford J. Landry, Director, Land Systems Division,
Systems Planning Corporation.

1II-A-1

1II-A-2

BACKGROUND

MOE was mission availability

DEFINITION

Hitting the ground

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HITTING THE GROUND

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B. "Suppression in Che TRADOC" -Mr. Roger Willis, Operations
Research Analyst, Chief of Phenomenology and Model Processes
Branch (TRASANA)

SUPPRESSION IN TRADOC MODELS

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11. BATTLE

MODEL

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DYNTACS

LEGAL MIX

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SUPPRESSED STATES

ACTIVITIES SUPPRESSED

NOT

DIRECT

FIRE

YES

MOVE

YES

OBSERVE

YES

COMMUNICATE

FDC

COUNTERPRODUCTIVE

NO?

YES

EFFECTS

DURATION OF

EXP.

STOCH

MATRIX

EXP.?

SUPPRESSION

STOCK?

INPUT

CONDITIONS

TYPE OF ROUND

NO. OF ROUNDS

TARGET TYPE

TYPE OF ENGMT

ATKR OR DEFNDR

FORCE RATIO

MISS DISTANCE

GROSS

TARGET COVER

NON-LETHAL HITS

KILL PROB.

HUMAN FACTORS

ELEMENTS NOT

SUPPRESSED

ARTY

ARTY .

ARTY

MNVR

IlI-a-3

FOURCE SUPPRESSION

SUPPRESSION DATA

CARMONETTE

CD EC

INPUTS

(50% PROBABILITY

WEAPON

(NEUTRALIZATION

SUPPRESSION AREA*

WT. PER RD)

PER ROUND)

8 INCH

155 MM

81 MM

0.70

105 MM (TANK)

0.80

50 CAL. MG
(5 rdg)

0.06

NORMALIZED: 35,300 M2 - I FOR 155

CONDITIONS FOR SUPPRESSION

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IlI-u-6

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REDUCED VULNERABILITY

RATIONAL CONTROLLED OPERATIONAL COMBAT

THEORY TEST* TESTS DATA

ONLY ONLY

RELATIONS BETWEEN FACTORS
NUMERICAL VALUES

CONCLUSIONS

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. IMPOSSIBLE?

SLIDE #1

CCEC

SUPPRESSION

EXPERIMENTATION

slide n

TYPES OF SUPPRESSION

- REASONED SUPPRESSION

- UNREASONED SUPPRESSION

- PHYSICAL SUPPRESSION

III-C-2

SLIDE //I

DATA DESIRED

- PROXIMITY

- ^ 50%

- ) 90%

- VOLUME

- } 50%

- > 90%

SLTDE #4

EXPERIMENTS

I)UCS

DACTS

SASF.

SUP EX I
SUPEX III

m-c-3

SLIDE #5

DUCS

- SIMUIATED FIRE

- SOUND RECORDINGS

- TASK LOADING

- USE OF ACTUAL WEAPON

SLIDE #6

•; 3

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D A C T S

- LIVE FIRE

- PLAYERS WITH PERISCOPES

- CONCEALED AND OPEN

- ATTACH BY WEAPON SQUAD

- VARIABLE DISPERSION

lll-C-4

SLIDE in

S A S E

- LIVE FIRE

- RIFLES AND MACHINE Cl' NS

- STEREOTYPE SCENARIO

- CLOSE CONTROL OVER MISS DISTANCE

- IMPACTINC AND OVERHEAD ROUNDS

- PATTERN AND VOLUME OF FIRE

- DAY AND NIGHT

- INDIVIDUAL AND UNIT SUPPRESSION

- COMBAT TRAINING

SLIDE If 8

SUP EX I

- LIVE FIRE

- ALL WFJlPONS FROM RIFLE TO fi INCH J

SLIDE #9

SUPEX III

- INDIRECT FIRE ONLY

- EQUIVALENT CHARGE DETONATIONS

ASPECT TO SUPPRESSEE

- SINGLE ROUND AND VOLLEY

SLIDE 15*10

MATHEMATICAL EQUATION

RMD - Ac BP<S>

WHERE

RMD - RADIAL MISS DISTANCE

A,B - FITTED PARAMETERS

r(S) - PROBABILITY OF SUPPRESSION

e - 2.718

III-C-6

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SLID!! Oil

WEAPON

M-3

M-16A1

M-2

M139

MK19

PROXIMITY REQUIRED FOR SUPPRESSION
(DIRECT FIRE)

P(S) - .5
DAR SUPEX

P(S)

PAR

SUPFX

SLIDE il 12

PROXIMITY REQUIRED FOR SUPPRESSION
(INDIRECT FIRE)

WEAPON

P(S) - .5

F(S) -

DAR

SUPEX

SUPEX IIT

DAR

SUPEX

60MM

81MM

105 HOW

118

105 HEP-T

2.75"

155MM

144

106

104

8 IN.

392

257

169

126

III-C-7

ANGLE OF NO. C

CALIBER

MISS __
DISTANCE

FRACTION OF

TARGET KILLED

TARGET DENSITY

I (LITTON
^ MODEL)

SUPPRESSION

PROBABILITY

CDEC SUPPRESSION EXPERIMENTATION
BY Marion R. Bryson
ABSTRACT

During the years 197S - 1978, the US Army Combat Developments
Experimentation Command conducted a series of experiments to
study the phenomenon of suppression. This paper describes
briefly the experiments, the reports generated, and the
availability of these reports.

1. INTRODUCTION:

Starting in 1975, USACDEC, Fort Ord, California, began
a study of the effects of direct and indirect fire suppression.
The purpose of this series of experiments was to evaluate
what was called "reasoned suppression". Reasoned suppression
was defined as that suppression resulting from a conscious
decision by the suppressee to take cover because of perceived
physical danger. This is as opposed to physical suppression
(injury, death, obscuration) and unreasoned suppression
(panic, fear, etc.). These experiments culminated in a
series of reports. These reports are summarized in the
following paragraphs. Following that is a brief comparison
of the results of each of the report.

2. SUMMARY OF REPORTS:

a. Degradation Under Control Stimuli (DUCS) , April 1975

(1) Purpose : This experiment was conducted to determine
capability and methodology to conduct suppressive- type ex¬
periments and to compare the relative suppressive effects

of the .50 cal and 7.62mm machineguns.

(2) Objective :

(a) To determine CDEC's current capabilities to induce
suppressive effects during field experimentation.

(b) To identify current shortcomings in instrumentation,
equipment, and methodology.

CDEC Suppression Experimentation

(d) To obtain subjective opinions of the suppressive
effects of selected small arms.

(e) To examine the suppressive effects of the .50 cal.
machinegun simulated experimentally.

(f) To examine the suppressive effects of the 7.62mm
machinegun simulated experimentally.

(g) To evaluate the relative suppressive effects of
the 7.62mm machinegun simulated experimentally.

(3) Description :

(a) DUCS was a simulated live-fire experiment designed
to evaluate the relative non-lethal suppressive effects

of machinegun fire on an ATM gunner. A total of 48 record
and 12 baseline trials were conducted.

(b) In each trial, two players, in the roles of ATM
gunners, were evaluated on their ability to observe and
simulate firing at attacking threat vehicles while being
engaged by simulated fire.

(c) The threat consisted of two armored reconnaissance
vehicles which advanced on the players' position utilizing
the bounding overwatch technique. The sequence in which the
threat vehicles moved and fired was developed based on the
bounding overwatch technique and maximum use of the terrain
for cover and concealment.

(d) Players were carefully selected to insure proper
motivation, intelligence, experience and aural and visual
acuity.

(4) Major Findings; The major findings in this ex¬
periment were provided in terms of answers to questions
designed to satisfy experimental objectives as follows:

(a) To what degree do the effects of .50 cal. machine-
gun fire degrade the performance of an enemy antitank gunner?
When subjected to simulated ,50 cal. machinegun fire, the
mean tracking (productive) time of player personnel was
degraded approximately 57 percent.

iii-c-io

CDEC Suppression Experimentation

(b) To what degree do the effects of 7.62mm machinegun
fire degrade the performance of an enemy antitank gunner?

(1) When subjected to simulated 7.62mm machinegun fire,
the mean tracking time of player personnel was degraded
approximately 61 percent.

(2) When subjected to the fire of a 7.62mm machinegun
firing blanks, the mean tracking time of player personnel
was degraded approximately 44 percent.

(c) Which machinegun is the more suppressive weapon
under controlled conditions? Using the same volume and
technique of fire, it was not possible to detect a statisti¬
cally significant difference between the suppressive effects
of the two weapons examined.

(5) Report Availability: This was an internal CDEC

methodology study. The final report is available for exami¬
nation at Fort Ord.

b. Dispersion Against Concealed Targets (DACTS) , July 1975

(1) Purpose: DACTS was conducted to provide data to the
US Army Infantry School (USAIS) for analysis to determine the
impact of various dispersion levels on the effectiveness of
thi future rifle system.

(2) Objectives :

(a) To provide data to evaluate the impact, of variations
of the man/rifle system's effective three-round burst dis¬
persion on the effectiveness of the individual rifleman
against various types of threats.

(b) To provide data on the phenomenon of suppression
inducted by the effect of small arms fire.

(3) Description : .DACTS was designed to provide data to
evaluate semi-automatic fire and six burst dispersions
obtained with modified M16 rifles (4.32mm) and standard
M16A1 rifles. The experiment was conducted on three live-
fire ranges. Types of targets engaged were concealed
stationary, visible stationary and visible moving. Addi¬
tionally, the experiment provided data on the suppressive

lil-C-ll

CDF-C Suppression Experimentation

effects of the weapons employed and, through side tests,
provided data on the distribution of personnel in an
attacking squad (TERTEST) , training implications related
to engaging moving targets (Moving Target Range Side Test),
and the ability of personnel to discern the proximity of
rifle fire (Round Locating Side Test).

(4) Major Find ings :

(a) Data and information collected in DACTS were keyed
to the following questions:

1 What level of dispersion maximizes the effective¬
ness of the individual rifleman engaging visible targets?

2 What level of dispersion maximizes the effective¬
ness of the individual rifleman engaging concealed targets?

£ What level of dispersion maximizes the effective¬
ness of the fire team engaging visible targets?

£ What level of dispersion maximizes the effective¬
ness of the fire team engaging concealed targets?

(b) A preliminary data analysis indicated trends in
the effects of burst dispersion on the performance of both
the individual rifleman and the infantry fire team. However,
a full data analysis was conducted by USAIS which provided
conclusions and inferences on the specific effects of the
variations in burst dispersions,

(5) Report Availability : A copy of the report may be

obtained from bDd. ( A D : b b 05 701)

c. Suppression Experimentation Data Analysis (DAR)
Report, April 1976. t

(1) Purpose : The DAR provides the results of a data
analysis on the suppressive effects of direct and indirect
fire on soldiers under simulated combat conditions.

(2) Obj ectives :

(a) To determine the proximity of fire, in meters, re¬
quired to suppress an antitank glided missile (ATGM) gunner
with probability of 0.S and prob ility of > 0.9.

II1-C-12

CD EC Suppression Experimentation

(b) To determine the volume of fire required to obtain
SO percent and 90 percent suppression of ATGM gunners.

(3) Description ;

(a) The analytical results in this report addressed
several types of suppression:

1^ Physical Suppression. Degradation of performance
of an~individual or unit due to physical incapacitation such
as death, injury, obscuration, or other physical constraints.

2 Unreasoned Suppression. Degradation of performance
of an“individual or unit due to immediately uncontrollable
psychological or physiological factors such as panic, fear,
fatigue, etc.

^ Reasoned Suppression. Temporary degradation in the
quality of performance of a soldier or unit due to avoidance
of a perceived threat from enemy weapon systems.

Cb) Data used in the analysis contained in this report
came from several suppression experiments conducted by
CDEC. The experiments included are the Small Arms Suppression
Experiment, Phase II (SASE II); Suppression Experiment, Phase I
(SUPEX I) ; Suppression Experiment, Phase II (SUPEX II); and
/rtillery CDEC Experiment, Suppression (ACES),

,(4) Major Findings : The data analysis revealed that:

(a) The probability of suppression is influenced by the
proximity of fire in an ordered and predictable manner.

(b) The proximity of fire or radial miss distance in
meters can be modeled by an experimental equation.

(S) Report Availability: A copy of this report may be
obtained from DDd (A10T' ITT O' 57 9L) .

d. Suppression, July 1976

(1) Purpose : This bulletin is designed to provide

commanders and troops in the field with an understanding and
appreciation for the importance of suppression.

(2) Objectives :

(a) To provide information on the techniques of employing
weapons in suppression roles and the relative suppressive ca¬
ll j-c-l 3

CDEC Suppression Experimentation

pabilities of various weapons and countermeasures available
to reduce the suppressive effects of enemy fire.

(b) To discuss training implications.

(3) Description :

(a) The information contained in this bulletin is based
upon the results of a number of live fire field experiments
conducted by the US Army Combat Developments Experimentation
Command in 1975 and 1976.

(b) The bulletin presents various combat situations
and then suggests different options the commander may exer¬
cise to provide suppressive fires and reduce enemy effective¬
ness.

(4j Major Findings; The findings in this bulletin are
p r e s en t ed” i n t e rms of th e results obtained after exercising
various options in a given combat situation.

(5) Report Availability : A copy of this report may be
obtained from the USXCDEG Library.

e. Small Arms Suppression Evaluation Phase II (SASE II),
August 1976

i •'

(1) Purpose ; The SASE II experiment was conducted to
provide data on the suppressive effects of the M16A1 (5.56mm)
rifle, the M60 (7.62mm) machinegun and the M2(,50 cal) machine
gun.

(2) Objectives :

(a) To obtain and quantify the level, duration and thres¬
hold of the suppressive effects that selected direct fire
weapons have on defending infantry.

(b) To identify and quantify the effects that selected
variables have on the suppressive effects of selected direct,
fire weapons employed against defending infantry.

(3) Description : For this experiment, suppression is
defined as! The temporary degradation in the quality of
performance of an individual due to avoidance of a perceived
threat. Empirical data were collected on the ability of
soldiers to perform combat-related tasks while receiving
fire. The conditions under which the fire was delivered

1 -*-J ' V1 «'i ! « WH :W.

CDEC Suppression Experimentation

were controlled and varied by the experiment design. There¬
fore, data collected on variations of performance are mea¬
sures of suppression. The experiment was conducted in
eight parts with each part designed to contribute selected
data in support of the overall purpose and objectives of
the experiment. During each part., the suppressive effects
of fire delivered against infantrymen concealed in defensive
positions were evaluated. Two supplemental data analysis
reports were also prepared for the SASE II Experiment:

(a) SASE II Analysis Report (Vol II ) July 1976

(b) BDMSC SASE II Analysis Report August 1976

(4) Major Findings:

(a) The M2 machinegun was shown to be significantly
more suppressive than the M60 machinegun, which in turn,
was significantly more suppressive than the M16A1 rifle.

(b) The number of rounds (e.g., 3 vs. 6) of ball ammuni¬
tion per burst of automatic fire has little or no effect on
the suppressiveness of the fire. However, the time interval
(e.g., 4 sec vs. 12 sec) between bursts has a significant
effect,

(c) Suppresive fire delivered in small bursts with
shurt time intervals between bursts appears to be most
efficient for delivering suppressive fires.

(d) The degree that a soldier is suppressed by incoming
fire can be approximated by a mathematic; l model which in¬
cludes the natural logarithm of his distance to the incoming
fire.

(e) Classes (or techniques) of fire affect the suppressive¬
ness of the fire. Classes of fire which result in a random
distribution of fire throughout the target area are more
suppressive than classes which result in fire being distri¬
buted in a systematic pattern.

(f) Soldiers who have received indoctrination stressing
the lethality and dangerousness of weapon systems are more
suppressed (401) by the systems than soldiers who have not
been indoctrinated.

(g) Soldiers operating independently were found to be
more suppressed (43% to 115%) under similar conditions than
collocated soldiers operating in groups.

I1I-C-15

CDEC Suppression Experimentation

(h) Soldiers defending from frontal parapet foxholes
were significantly less suppressed (624) than soldiers de¬
fending from standard foxholes.

(i) Suppression is affected both by the overall situa¬
tion under which fires are delivered and by the individual
bursts of fire.

(5) Report Availability: (AD B013211)

The availability of these reports are as follows:

(a) SASE II Experimental Report - DDC (AD BQ132102)

(b) SASE il Analysis Report (Vol II) - USACDEC Library

f. Suppression Experiment (SUPEX), February 1977

(1) Purpose: The SUPEX experiment was conducted to pro
vide comparative evaluations of the suppressive effects of
selected weapon systems ranging from the M16A2 rifle to the
8-inch Howitzer.

(2) Objectives :

(a) To determine the proximity of fire required to
suppress a threat antitank missile gunner with a single
round or burst with probabilities of .5 and .9.

(b) To determine the volume of fire required bv each
weapon1 system to sustain 50 % and 901 suppression of a threat
element employing antitank guided missiles along 100m and
SOOm fronts.

(3) Description : SUPEX was conducted in two phases.
During Phase I, the W16A1 rifle, M3 submachinegun , .50 cal.
machinegun (MG), 20mm cannon, and 40mm High Velocity Gre¬
nade Launcher (HVGL) were evaluated. The latter three
weapons were tested with the players located in individual
protective bunkers and by firing at targets immediately to
their front. A silhouette target, which represented the
player and over which he had control, was placed directly
in front of the bunker and electrically wired in such a
manner that when the player raised his periscope, tho
silhouette went up and when the player lowered his periscope

TII-C-16

COEC Suppression Experimentation

the silhouette went down. The players' mission was to
acquire target tanks and simulate firing an antitank
missile at these targets located at ranges of approximately
1400 meters. The players were instructed to respond to in¬
coming rounds by lowering or raising their periscopes as
they believed they would if they were the silhouette
immediately to the front of their foxhole. The raising
and lowering of the periscopes was automatically recorded
and an analysis performed on the percent of the players
that suppressed as a function of the distance that a round
impacted from the player's silhouette.

(4) Mai or Findings : The findings were presented in the
form of probability curves and data tables. These findings
revealed the proximity within which single rounds and five-
round bursts of various weapon systems must impact to
achieve a .5 and .9 probability of suppression.

(5) Report Availability: A copy of this report may be
obtained FfonTUD'C (BO 17 11 6 JT

g. Suppression Experimentation Supplemental Data
Analysis (SESDA) , May 1977

(1) Purpose : The SESDA report was prepared to provide

su] pression data results from selected trials of the Small
Arm? Suppression Experiment (SASH II) conducted by CDEC.

(2) Obj ectives :

(a) To determine the proximity of fire, in meters, re¬
quired to suppress an individual infantryman with probability
of 0.5 and probability of 0.9 under each of the experimenta¬
tion conditions.

(b) To determine the effects on the suppression of
infantrymen due to:

Rate of fire

2^ Selected patterns of weapon fire
3 Type of ammunition at night.

I1I-C-17

CDEC Suppression Experimentation

(3) Description : Empirical data were collected on the

ability of soldiers to perform combat related tasks while
receiving fire. The conditions under which the fire was
delivered were controlled and varied by the experiment
design. Data collected on performance variations provide
measures of the effects of the experiment treatments on
suppression. The experiment was conducted in parts with
each part designed to contribute selected data in support

of the overall purpose and objectives of the experiment.

(4) Major Findings;

(a) In general, a six-round burst of fire from the M2
machinegun has a higher probability of suppressing players
than a six-round burst from the M60 machinegun under all
conditions examined.

(b) The probability that a six-round burst would
suppress players generally decreased for both the M2 and
M60 machinegun as the radial miss distance of the impacting
fire increased.

(c) Generally, bursts of fire using the traversing
patterns had a higher probability of suppressing players
at a given miss distance than bursts of fire using the
pseudorandom techniques of fire.

(d) In general, bursts of fire directed overhead by
the M60 machinegun at a player's position had relatively
the same probability of suppressing the player as did
bursts of fire directed into the berm forward of the
player.

(5) Report Availability: A copy of this report may

be obtained from the CDEC Library.

h. Suppression Experiment IIIA (SUPEX IIIA), June 1978

(1) Purpose : The SUPEX IIIA Experiment was conducted
to determine the methodology which would provide the most
credible field environment to gather suppression data
while insuring adequate player safety.

(2) Objectives :

(a) To compare the probabilities of suppressing an ATGM
gunner (with simulated rounds) when using an "open" versus
a "closed" foxhole.

II1-C-18

CDEC Suppression Experimentation

(b) To compare the probabilities of suppressing an
Antitank Guided Missile (ATGM) gunner in a covered foxhole
when high explosive projectiles were detonated and when
simulated rounds were detonated.

(3) Description : SUPEX IIIA was a methodology

experiment designed to compare individual responses to
suppression effects induced by selected live, indirect fire
munitions (81mm and 155mm) and their simulated rounds,

and to evaluate two foxhole types. Also, to select the
best techniques and procedures to be used in future
suppression experiments while insuring the absolute safety
of the players.

(4) Major Findings:

(a) There is no statistically significant difference
between live round, closed foxhole conditions, and the
simulated round, closed foxhole condition with a 81mm round.

(b) There is no statistically significant difference
between the open and the closed foxhole using a simulated
81mm round.

(d) The simulated/closed condition is significantly
less suppressive than the simulated/open condition for
the .15Smm round.

(5) Report Availability: A copy of this report may
be obtained from the CDEC Library.

i. Suppression Experiment 1 1 1 B (SUPEX 1 1 1 B) , November

1978

(1) Purpose : The SUPEX 1 1 1 B was conducted to generate
data and measure the reasoned suppression produced by
statically detonated surface bursts of bOmm mortar, 81min
mortar, lOSmm Howitzer, and 155mm Howitzer rounds.

(2) Objectives :

(a) To determine the probability of suppressing an
Antitank Guided Missile (ATGM) gunner with single rounds
as a function of detonation distance and aspect angle from
the gunner.

Ill-C-19

COEC Suppression Experimentation

(b) To gain insights into the probability of suppressing
an ATGM gunner with volley fires from 105mm and 155mm
Howitzers (surface burst).

(c) To gain insights into the effect of obscuration on
the probability of suppressing an ATGM gunner with the
various type detonations. This objective was added to the
test after the project analysis was published.

(3) Description: The experiment was designed to
examine the players ' responses induced by the exploding si¬
mulated munitions. It was a one-sided live fire experiment
employing statically detonated 60mm, 80mm, 105mm, and 155mm
simulated rounds. These simulated rounds were detonated as

5 round bursts. Player personnel were placed in open foxholes
n close proximity to the detonating munitions. Using an
instrumented prototype sight, players were required to detect
and simulate engagement of a moving target vehicle while sta¬
tically detonated munitions were exploded on the ground at
specified distances and aspect angles from his position.

Limited volley fire trials were executed to gain insights into
the effects of volley fire (105mm and 155mm simulated rounds)
compared to single round fire on the reaction of an individual
soldier. It was assumed that 6 tubes of artillery would fire
a volley at a given point with no adjustments being made on
the impacting rounds. ,

(4) Major Findings:

(a) For any given range and round size, the most
suppressive detonations observed were directly in front of
the player (0 degrees), The observed least suppressive
detonation varied for each round size, but always behind the
player. (The least suppressive aspect angle for 60mm, 81mm,
105mm and 155mm was 180, 150, 180 and 210 degrees, respectively)

(b) The most suppressive detonations during the volley
fire were located to the player’s front (0 degrees) and the
least suppressive detonations were generally at 90 or 180
degrees.

(c) For single round detonations, when obscuration of
the target vehicle was reported, the angle between the
target vehicle and the detonation measured from the player's
vantage point was generally between + 45 degrees.

11I-C-20

btiiiuiiaMlmjliilitii.ii ,..r >'

. ..‘.L-.it .. t j.v. '• t* * . -V .Ml LL

\ i

CDEC Suppression Experimentation

(d) Human factors questionnaire results and individual
interviews showed the players regarded the experiment as
a very realistic training, particularly during the volley
trials.

(5) Report Availability:
obtained From" DT5C ( B Or^ITy.

A copy of this report may be

3. RESULTS SUMMARY : Table I shows the weapons which are
treated in each oT the reports described in the preceding
paragraphs. Tables II and III compare the results of these
experiments. DAR is the Data Analysis Report based on
several sources of suppression data.

m-c-21

TABLE I

PROXIMITY OF FIRE REQUIRED FOR GIVEN
PROBABILITY OF SUPPRESSION

WEAPON

DAR

PCS')-.

SUPEX

SUPEX I.II

DAR

P(S)«

SUPEX

. 90
SUPEX

M-3

M- 16A1

M-2

Ml 3 9

MK1 9

60mm

81mm

105 How

118

4 6

105 HEP-T

4 9

2.75"

155mm

144

106

104

392

257

169

126

TABLE II
II1-C-23

VOLUME OF FIRE NECESSARY TO CAUSE GIVEN PERCENT
OF SUPPRESSION OVER A 100 (or 500) METER FRONT
(RDS per minute)

50t 901

WEAPON

FRONT

DAR

SUPEX

DAR

SUPEX

M-3

100

103

135

342

450

M-16A1

100

128

293

413

M* 2

100

M139

100

MK19

100 •

60mm

500 .

81mm

500 *

105 How

500

105 HEP-T

500

2.75"

500

155mm

500

For larger caliber indirect fire weapons, the two integrating
techniques differ markedly. The repetition of the 10 and the
2S in the SUPEX is a peculiarity of the scenario used, not an
indication that those weapons are equally effective.

TABLE III
Ill-C-24

"Suppression v/Datfl from Yom Kippur War" - Mr Paul Kunselman,
Physicist with Tactical Operations Office, AMSAA

SI, IDF, II 1

IIS ARMY MATERIEL SYSTKMS ANALYSIS ACTIVITY
SUPPRESSION ESTIMATES IN DIVLEV
P. KUNSELMAN
T. ROUSE
K . BUTLER

SLIDE 112

SUPPRESSION BY EIRE IN DIVLEV

o DIRECT KIRK SUPPRESSION OF DIRECT FIRE WEAPONS

o ARTILLERY SUPPRESSION OF MANEUVER UNITS
(DIRECT FIRE WEAPONS)

o ARTILLERY SUPPRESSION OF ARTILLERY WEAPONS

SLIDE II 3
DIVLEV OVERVIEW
o TWO SIDED WARGAME

o PLAYER CONTROLLED, COMPUTER ASSISTED
o RESOLUTION - COMPANY MANEUVER UNITS
- ARTILLERY BATTERY
o SEVERAL DIVISIONS ON EACH SIDE
2 PRIMARY PRODUCT - DETAILED TIME
DEPENDENT COMBAT SCENARIOS

II1-L-2

SI, 1 DK ///,

SUPPRESSION BY FIRE
FEAR - PRUDENCE - OBSCURATION

SLIDE // 5

DIRECT FIRE - > DIRECT FIRE

ASSUMPTIONS

o FRACTION OF DIRECT FIRE WEAPONS IN SUPPRESSED STATE (\)

. . “ CK (X)

X =l-o

C>0, SUPPRESSION CONST.

F(X) =$ SOME FUNCTION OF SUPPRESSING FORCE STRENGTH, (X)

o ATTACKING FORCE: DEFENDING FORCE = 1:1

o DEFENDER NOT "HARDENED" BUT IN HASTY PREPARED DEFENSIVE SITE

o THE ATTACKING CDR WILL MAXIMIZE THE NUMBER OF ATTACKERS
REACHING THE DEFENDER'S POSITION BY ALLOCATING 1/1 OF
ATTACKING FORCE TO RESERVE & OVERWATCH AND 2/3 OF ATTACKING
FORCE TO ASSAULT.

111-11-3

SLIDE II 6

DESIGN SCENARIO

DEFENDER (M)

ATTACKER (N)

KILL RATE

SLIDE #7

DIRECT FIRE SUPPRESSION CONSTANT
Po = .036 DEFILADE TANKS K I Li ED/M I N/TANK l/l'N
Pd - ,74 MOVING EXPOSED TANKS K I LLKD/H ! N/TANK WPN
T - 5 MIN

SUPPRESSION

CONST

% DEFENDER ASSAULT FORCE

SUPPRESSED REMAINING

Y (T)

33%

. 16N

a/%

. 49N

(23% LOST)

SLIDE //«

DIRECT FIRE - -> DIRECT FIRE

FRACTION POTENTIAL KILL

TARGET SUPPRESSED FUNCTION AT TARGET

SI-1 IJIi if 9

TANK__

LOSSES

ACTUAL

FORCE

STRENGTH

LOSSES

DIVLEV

CASE 1

BLUE

4.9 - i:

RED

1.3 - 1

CASE 2

BLUE

7.5

RED

9.8

CASE 3

BLUE

RED

SLIDE #10
TANK LOSSES

DURATION
20-57 (60)

6 (45)

10 (53)

' STARTING

GAME

FORCE

STRENGTH

CASE 1

BLUE

RED

CASE 2

BLUE

RED

CASE 3

BLUE

RED

ACTUAL DIVLEV
LOSSES LOSSES

2 1.4

7 7.3

3 2.4

11 10.8

0 0

6 6.6

ACTUAL DIVLEV
DURATION DURATION

60 MIN 60 MIN
45 MIN 45 MIN
53 MIN 53 MIN

SI, 1 1)K It 1 1

MANEUVER UNITS

NAB - If ARTY BTRYK TARGETED ON UNIT
TPCP « #300 METER SEGMENTS IN FRONT OF

UNIT

.693 (NAB (t)/TFOP (t))
(NAB - TFCP)

.386 (NAB (t) /TFCP (t) )

(NAB =» TFCP)

PORTION OF UNIT SUPPRESSED IS NOT ALLOWED TO MOVE,
FIRE, OR BE FIRED ON BY DIRECT FIRE WEAPONS

Sm (t) ■ 1 - e

- .5

Sa (t) ■ 1 - e

- .75

SLIDE II 12

ARTILLERY SUPPRESSION OF ARTILLERY UNITS

1BTRY vs 1 BTRY

o FIRST ATTACK; TOTAL SUPPRESSION DURING PERIOD OF

ATTACK AND SUBSEQUENT 15 MIN (SMALL
DISPLACEMENT)

o SUBSEQUENT
ATTACKS :

(WITHIN 5 HRS): TOTAL SUPPRESSION
DURING PERIOD OF ATTACK AND SUB¬
SEQUENT 30 MIN (LARGER DISPLACEMENT)

ROUNDS MUST FUNCTION WITHIN 150 METERS OF BTRY CENTER

ARMORED ARTY, MISSIONS BEING PERFORMED ARE COMPLETED
BEFORE SUPPRESSION TAKES EFFECT.

FEAR

SLIDE 1112

SUPPRESSION BY FIRE

PRUDENCE

OBSCURATION

OTHER SUPPRESSION MEANS

o SMOKE DELIVERED BY ARTILLERY
o DEAD TIME - DIRECT FIRE KILL RATES
o EW

o FIGHTING EFFICIENCY

1II-D-8

"Suppression of Enemy Air Defense (SEAD) " - LTC Kenneth
Redding, United States Air Force Repre8entativc at Fort Sill

SCAD - Lt Col Redding

General Dlngcs, Ladles and Gentlemen, this afternoon I offer a departure
from this morning's speakers. That Is, I will present no models, no specific
dates, nor will I get deep Into rolea and missions. Instead, I will give a
report on USAF efforts In the area of Suppression of Enemy Air Defense (SEAD)

, and will conclude with an Idea for your consideration as we go into our study

groups.

In February 1979, General Creech, Commander of Tactical Air Command (TAC),
directed the Commander of Green Flag to begin work on a SEAD concept. Let me
explain that Flag organizations in TAC are tasked with conducting exercises
which evaluate units, equipment and concepts. For example, the Red Flag involves
combat exercises. Blue Flag deals with command and control, Gray Flag tests
maintenance, and now, Green Flag will be responsible for SEAD. In April 1979,

Green Flag queried various USAF units attached to Army Installations for Inputs
into the directed study. Today, this week, there is a Green Flag conference at
Eglln AFB, Florida which Is attempting to define terms and quantify data In much
the same matter as we are doing In this symposium. After Grean Flag develops a
command approved concept, the plan Is to test lt In a Red Flag/Blue Flag envlron-
9 ment. Now I would like to move from current efforts to future requirements.

, Name one factor that colors the entire USAF Offensive Air Support (OAS)

picture and you would have to pick the Soviet mobile SAM concept with Its redundant
target coverage. It has forced us to change our tactics from those used In
Southeast Asia to those presently used, i.e,, low level, In order to Increase
aircraft survivability and, In the long term, OAS effectiveness.

I1I-E-2

--.tv, -v .

Closely linked to survivability is effective suppression which lends me to
my main point: TACAIR must have suppression, specifically SEAD (SAM and AAA)
in order to be effective In the hostile environment previously mentioned. Now
there are, generally speaking, two ways we can obtain this suppression:

1. We (USAF) can provide SEAD ourselves by forming a Strike/Support aircraft
package. This fighter group would be composed of a given number of strike
aircraft led by a pathfinder or escort fighter aircraft. Accompanying the strike
element would be support aircraft with specialised roles, l.e., chaff dispensing,
Mlg Cap, and electronic counter measures. These aircrafts would be preceded by
reconnaissance aircraft which would provide the main force with target information.
Most of us can remember the large aircraft raids into North Viet Nam. For
illustration purposes let's say ths raid force was 100 aircraft. That looked
Impressive, 100 aircraft going up North at one time, but on closer examination you
would find maybe 50 of the aircraft carrying Iron bombs? the rest were support
aircraft. Now with the force just described, you could expect an acceptable degree
of suppression but look at the cost. Since we deal with a finite number of
aircraft we oust get the support aircraft from somewhere. So, we rob Peter to pay
Paul. 2. Better that we try to maximize the number of strike aircraft available
for OAS. We can do this by utilizing the other means of suppression - joint
SEAD. By using Army assets, ouch as artillery, Vulcans, armed helicopter, mortars
or the long range Nike, together with USAF capabilities you have the best of the
two suppression systems. I conclude by restating the USAF believes in READ, we
lead it to survive tomorrow's battle.

"Human Behavior in Combat" - COL (Ret) Trevor N. Dupuy
Noted Author, President, T. N. Dupuy Associates

1II-F-1

HUMAN BEHAVIOR IN COMBAT:

WITH A FOCUS ON SUPPRESSION

Colonel T. N. Dupuy

I have been asked to provide some Insights gleaned Cron military history about
human behavior In combat, aa It may be rolevant to our conference topic of
"Suppression".

Before I address myself to the specifics of this, I want to make sure that you
all recognize that there are tvo kinds of military history:

There la military history cited (often erroneously) to support preconceived
Ideas, and there Is analytical military history based upon objective and
comprehensive (as opposed to selective) assessment of nil available and relevant
facts. Obviously, no one would plead guilty to serving up distorted military
history. To use a non-military historical analogy, all bootleggers of the
1920's and 30'e assured their customers that they were soiling stuff right off
the boat} none would admit that he was really peddling home-grown and colored,
row corn whiakey.

'So, you are warned. Be skeptical about all military historical facts cited to
you — Including mine. But Just because you are skeptical, don't discount 1 t ;
merely make sure that you are not being sold a bill of goods.

Let ire give you some examples of distorted military history — relevant to my
topic of human behavior in combat — from recent articles In military Journals.

It le popular these days to try to encourage the troopB by assuring them that it
Is perfsctly reasonable to expect that we can and should be uble to fight out¬
numbered and win. My examples are of this genre of encouragement, via "military
hlatory" in military journals.

In one recent article the author gave several instances of "fighting outnumbered
and winning." Three particularly interested me:

! i

1. The Spartan defense of Themopylae.

2. Wellington's victory over Napoleon at Waterloo.

3. The American recovery and victory over the German onslaught at the
Battle of the Bulge, in 1944.

There is just one problem about all of these examples. The victorious side
outnumbered the losing side by margins of two-to-one or greater. In all three
instances the losing side hod higher combat effectiveness than the winners,
but they were overwhelmed by superior numbers.

Ul-r-2

In another article, the author tried to demonstrate that relative numerical
strength Is unimportant to combat outcomes by reminding the reader that in
most of Cressy's Fifteen Decisive Battles of the World the numerically Inferior
force won. If this statement were true It would be a very powerful argument.

It's too bad that In eleven of those fifteen battles the numerically superior
force won.

In other words, these historical examples really demonstrated just the opposite
of what the authors were trying to prove. This sort of thing can give military
history a bad namaMt

On this matter of relevance of numbers, let me quote from Clausewltz - "If we...
strip the engagement of all the variables arising from Its purpose and circum¬
stances, and disregard (or atrip out) the fighting valuo of the troops Involved
(which Is s given quantity), ws are left with the bars concept of the engage¬
ment... In which the only distinguishing factor Is the number of troops on
either side."

"These numbers, therefore, will determine victory .. .superiority of numbers in
a given engagement is only one of the factors chat determines victory (but) Is
the most Important factor In the outcome of an engagement, so long as It Is
great enough to countarbalance all other contributing circumstances."

"This. . .would hold true for Greeks and Persians, for Englishmen end Mahrattas,
for Frenchmen end Germans."*

♦Karl von ClauaawltcE, On War
Book 3, Chapter 8

Over the past aaveral years I have been devoting a substantial proportion of my
time to consideration of the combat "variables" mentioned by Cleusewlti considering
not only those that are physical, tangible, end measurable, but those relating
to whet he called "the fighting value of the troops" — in other words, the
offsets of behavioral considerations on military performance and on battle out¬
comes. By physical variables I mean such things as the measurable effects of
weapons, of weather, of terrain, of armored protection, of vehicle capabilities,
end the like. By behavioral considerations I mean such things as the effects of
surprise, leadership, training, logistics capabilities, morels, end disruption.

My colleagues end I have estimated that there are 77 types of elements or
variables which Interact to produce combat outcomes and of these 18 are behavioral.
If we ever find a way to calculate such things — and some day I believe we will —
we will probably find the 18 behavioral far ora are potentially at least twice as
Important as the 59 physical elements or a'- rets.

Although I have not yet found a way to measure consistently the effects of the
variable factors that I call the "qualitative intangibles" — thosa that related
to what Clausewltz called the "fighting value (or quality) of the troops", and
to their leadership and control systems — I am satisfied that It la poaalble to
determine an overall, consolidated qualitative intangibles In any historical
battla, and that this consolidated vslue can be termed Relative Combat Effective¬
ness, or CEV. For Instance, analyses of more than 100 World War II engagements
have demonstrated aome very clear patterns of relative combat effectiveness of
the major participants. On the average, the Germans had a relative CEV of 1.2

III-F-3

vlth respect to the Western Allies -- the British and Americans. In other words,
100 Germans In ground military formations were roughly equivalent in combat
capability to 120 Americans or Britishers. The average Goman CEV with respect
to the Soviets was a whopping 2.5; or 100 Germans were the combat equivalent of
about 250 Russian soldiers in combat units. Similarly, in analyses of about 50
engagements of the 1967 and 1973 Middle East Wars, it is evident that the Israelis
had a relative Combat Effectiveness Value of about 2.0 with respect to their
Arab opponents; or, 100 Israelis in ground combat units were the equivalent of
about 200 Arabs.

Incidentally, It is this qualitative factor of Relative Combat Effectiveness -
what Clausewitr called the fighting value of the troops - that provides the
explanation for most cases In which a numerically inferior force — without the
benefit of defensive posture — defeated a larger force.

This might be s good time for me to mention one of the reasons why T bell eve
military history Is relevant to modern warfare, despite Its more sophisticated
technology end greater lethality of weapons.

For all of the changes that have taken place in weapons over the course of
recorded history, one Important element has remained constant: Man, and human
behavior In the lethal environment of combat, Becauae of that constant element
of war, some aspects of combat have not changed, and are as true today as they
were In the time of Alexander the Great.

Thus, if we wish to forecast the effects of new technology and untested weapons
on future combat, we must relate the known effects of this technology and these
new weapons to those things that have net changed — the timeless verities of
combat, I call them.

I hav < listed some Thirteen Timeless Verities of Combat which I believe provide
a base for forecasting. But tonight I only want to mention six, which I believe
are of particular importance to our purposes. These are:

1. The side which obtains the Initiative (either because of greater
strength, or greater skill) can apply greater combut power at a given time and
place then can its opponent.

2. Other things being equal, victory goes to the side with the combat
power preponderance; i.e., if opponents are comparable in skill and weaponry, and
allowance is made for defensive posture, superior numbers always win.

3. The combat power of a force which achieves surprise io substantially
enhanced, and can be doubled or tripled.

4. Fire kills; fire disrupts; fire suppresses; fire causes dispersion.

5. In combat all military activites are slower, less productive, and less
efficient than anticipated In peacetime tests, plans, and training exercises.

6. Combat is too complex to be described in a single, simple aphorism.

Let me amplify Just a bit about some of the behavioral factors that contribute
tc these timeless verities. Of course, not all of the behavioral factors are

II I -Mi

always operative. Take, for Instance, surprise . My colleagues and I have
learned from experience In analyzing a number of engagements, those In which
surprise Influenced the outcome, It Is possible to discern clear-cut effects
on both the mobility and vulnerability of the oppoelte forces. So, like
terrain, posture, weather effects, we can assign specific (and we hope relatively
precise) multiplier values to the effects of surprise on mobility and vulner¬
ability. Thus, I do not consider surprise to be an Intangible, like leadership,
or training, or experience.

Therefore, I call these behavioral variables — which may or may not be opera¬
tive in an engagement — "emphemeral, reactive factors." These are emphemeral,
and they are reactive, and of course (like the qualitative intangibles) they
are essentially behavioral.

For the moment I am assuming that disruption caused by a combat process other
than surprise will Include the effects of suppression. Further reeearch may
reveal that aupprasalon la a very distinct form of disruption, that can be
Dieasured or estimated quite Independently of disruption caused by any other
phenomenon — ettch aa a communications breakdown, which certainly would be de¬
grading and probably disruptive.

This leads me to mention again something you may have already heard me say a
couple of times: There la a need for rigor in the use of such overlapping — but
not synonomous — terms as disruption, degradation and suppression.

Someone In Working Group III said ve should not let ourselves get bogged down In
the details of definitions. My response 1st Let's be sure not only that we know
what we are talking about, but that we can communicate with each other.

In the light of the discussions we have had. It might ba useful if I gave you my
definition of suppresalon. It la similar to the one Colonel Pokomy put on
the acrean, but there Is a difference that might be significant:

"Suppression Is the degradation of hostile operational capabilities through the
employment of military action which has psychological or physical effects
Impairing the combat performance of enemy forces and individuals who have not
themselves been rendered casualties."

Note I focus tot on the means of suppression, but on the effects. Once we
fully understand the effect, the means will take care of themselves.

It is not appropriate in this presentation for me to make a pitch for any
particular methodology for trying to come to grips with this phenomenon of
suppression. 1 have some firm Ideas about this, which I have put in the form
of proposals and n "think piece" which was recently published In a profesnlonal
Journal.

But - at the risk of boring those who are In Working Group II - I do think
it Is appropriate for me to indicate how I think the experience of military
history can help us in our efforts to corns to grips with the elusive topic.

First, let me remind you that, by analysis of historical battla outcomes, It
has been possible to arrive at consistent values for the effects of surprise
and of superior combat effectiveness on the battlefield. Without military

Ill-K-5

iw 1 LV ■' . v ■** ■ •WWtkid- •■**A*il '• Mr i*» ~

l.l It- ■ 4 .

history it would have been utterly impossible to arrive at auch quantitative
values for these essentially qualitative, behavioral phenomena, ho one was
able to offer more than wild guesses about these combat processes effects until
my colleagues and I showed that they could be distilled from the materials
available in the laboratory of the soldier: military history,

I can see no possibility of arriving at values for suppression by any process
that is not equally dependent upon the resources available In this laboratory
of the soldier. No test, no experiment, can possibly reproduce the* conditions
which are the essence of suppression: human fear in a lethal environment,

Let me demonstrate why I believe something can be done about this matter — and
at the same time demonstrate why it is important that it be done. I’ll deal
with this latter point first.

It Is important that we be able to deal with the phenomenon of suppression
because it undoubtedly affects battle outcomes, and if we cannot find some way
of representing it in our models, then we cannot expect our models to give us
results in which we can have confidence. I hope that this is self-evident. I
hope that no "ne here thinks that if we cannot measure it, or reliably represent
it, that it can, therefore, be ignored, or only be considered every four yearB,
as suggested by Roger Willis.

Yet in effect, despite what Roger said we're largely ignoring the effects of
suppression, particularly in our more aggregated models.

Take CEM, for Instance. And I mention CEM only because it provides me with an
opportunity to make a very specific and very important point, net because it ia
any J.es6 reliable than other models in this or any other respect.

In CEf the effect of artillery fire is represented in ammunition tonnages. In
some uses of CEM, this artillery tonnage ia converted to "155HM equivalents . "

Now, then, let me refer you to a British Operations Research report of a poBt-
World War II analysis of several engagements in which Buppreasive effects of
artillery fire were assessed. By careful study of the data: opposite strengths,
casualties, amount of artillery ammunition expended, rates of artiller. fire,
nature of defensive protection, and the like, the British OR analysis were able
to determine a number of critical facta about the suppressive effect of artillery
fire, such us the duration and intensity of fire required to achieve n given
suppressive effect.

Now, one of the things that emerged clearly from this analysis was the following,
and I quota:

"There is the question of numbers of shells ae opposed to sheer weight — the
age-old argument in another form of field versus medium artillery. There are u
lot of jobs where the heavier shells are essential, either because of their
greater range or greater penetration and explosive powers. But where lighter
stuff can reach, and In capable of hurting the enemy, the evidence of these two
reports seems to be that the thing that counts most of nil is the number of
bangs. Clearly one 100 pounder shell it- better than one 25 pounder one. It is

Ill-r-6

on the other hand very questionable whether it 1* four timet better."*

•Number 2 Operational Research Section Report to the Army Council,
"Operational research In NW Europe," London, c. 1946, p 165.

(This report, Incidentally, it available in the Morris Swett Library here at
Fort Sill.)

Now, then, let's look at this British finding about suppression from historical
combat analysis, to see how it is relevant to the CEM method of measuring
artillery effect. If CEM were to show 100 tons of artillery ammunition fired
in a target area in a given period, that could be some 400 rounds of 8"
ammunition, it could be about 2,000 rounds of 155MM ammunition, or It could be
approximately 4,000 rounds of 105MM ammunition. Is there anyone in this room
who even without the British report — believes that the same suppressive effect
can be achieved with 400 8" rounds ip a given period of time as by 4,000 105MM
rounds In the same amount of time?

Dinner talks should not be long. They should be provocative. X hope I have
provoked some of you into exploring how combat historical data can help us
understand, measure, and represent the phenomenon of suppression.

m-h-7

SECTION IV ! WORK GROUP SUBJECTS AND PARTICIPANTS

Work Group I - Suppression Variables (Effects)

Members: Mr. Goldberg - Croup Leader

Dr. Esnderet, USA Inst Environ Medicine

Mr. Downs, BRL

Mr. Giordano, HEL

Mr. Kunselman, AMSAA

Mr. Bauman, Fort Knox

Dr. Plotkln, Mitre Corp

Colonel Buel, TRADOC/USAFAS Representative

Dr. Hegge, Walter Reed

Dr. Chambers, ARI

Work Group II - Suppression Variables (Causes)

Members: Mr. Hardison - Group Leader
Colonel Crawford, TSM Smoke

Lieutenant Colonel Stokes, USA Inst Environ Medicine

Dr. Burleson, TRASANA

Mr. Garrett, AMSAA

Mr. Landry, SPC

Mr. Lynch, Boeing Aerospace

Colonel LamonB, TRADOC/USAFAS Representative

Mr. C.R. Holt, Mitre Corp

Work Group III - Data Base Requirements

Members: Dr, Bryson, CDF,C - Group Leader
Colonel (Ret) Dupuy, TND
Captain LawBon, DNA
Mr. Cline, SPC

MrB. Shirley, Infantry School

Mr. Brown, Boeing Aerospace

Colonel Pokorny, TRADOC/USAFAS Representative

Dr. Leake, Armor A Eng Board

Mr. Loveless, USAFAS

Work Group IV - Suppression Modeling

Members: Dr. Payne - Croup Leader
Colonel Reed, CAC
Captain (P) Wallace, Fort Knox
Dr. Dub in, AMSAA
Mr. Cividan, ARI
Mr. Weiss, Litton
Dr. Blum, Vector Research

Colonel Slater, TRADOC/USAFAS Representative
Mr Porrecn, R&D Associates
Mr. Thorp, TRASANA
Mr. Millepaugh, USAFAS

Itf-1

Work Group V - Suppression/Countersuppresslon Combat and Training
Developments.

Members: Mr. Murphy, SAI - Group Leader
Major Graham, Infantry School
Major Money, Fort Rucker
Captain Gunderson, AMSAA
Lieutenant Colonel Bacon, TSM Smoke
Colonel Quinlan, TRADOC/USAFAS Representative
Major Johnston, Fort Bliss
Major Kalla, AMSAA

SECTION V: SECOND AND THIRD SESSION-WORK GROUPS' RESULTS

Group I:

Suppression Variables (Effects)

Group II:

Suppression Variables (Causes)

Group III:

Data Bass Requirements

•

Group IV:

Suppression Modeling

Group V:

Suppression/Countersuppression Combat and Training

Developments

A. Croup I: Suppression Variables (Effects)

Members: Mr. Goldberg - Group Leader

Dr. Banderet, USA Inst Environ Medicine

Mr. Downs, BRL

Mr. Giordano, HEL

Mr. Kunselman, AMSAA

Mr. Bauman, Fort Knox

Dr. Plotkin, Mitre Corp

Colonel Buel, TRADOC/USAFAS Representative
Dr. Hegge, Walter Reed
Dr. Chambers, ARI

In order to focus its effort Group I had the following goals and
questlons/leeues :

1. Coale:

a. Identify significant variables

b. Prioritize their importance

2. Queations/IsBueB :

a. What unlt/indivldual functions are suppressed?

b. What is the extent (quantity, time length) of suppression?

c. What are the aggregate effects of suppression on weapon
eyatem/unit?

d. How does unit/individual "battle history" affect suppression
vulnerabilities?

The Croup I Report

Suppression is something like Mnrk Twain's view of the Washington
weather "Everyone talks about it, but no one does anything about it".

Air conditioning may have helped to alleviate the Washington problem. Al¬
though there are some piecemeal efforts on suppression of dismounted troops,
the Army has yet to develop an overall view and hence an overall program on
what suppression is, what ceuaes it, and what its effects are.

. First a brief account of what haB been done -

- In connection with Army Small Arms Requirements effort and the
ASARS Battle model developed to support It, data was gathered from Vietnam
veterans about the results of suppression. These were consolidated into
seven categories of increasing severity, based on the results of suppression
on an individual's ability to move, shoot and observe. A CDEC experiment was
Chen conducted in which small arms of various calibers were fired overhead and
to the side of individual aoldiars - all combat veterans. These individuals
ralatad tha round and distance to one of the seven categories. The Infantry
School at tha seme time through a large scale questionnaire and a Delphi eval¬
uation tachnlque, quantified the amount of degradation of individual performance.
It was now possible to relate quantitatively the performance of a particular
round of small arms ammunition to its suppressive effect. These quantities
have bssn Incorporated into tha ASARS Battle model and are presently being
used in the SAW COEA.

Litton Corporation, under contract developed subjectively another model
to quantify tha suppression effects of exploding munitions, principally artil¬
lery rounds, against dismounted troops. While the model is still being used,

It hai not been well accepted. In order to develop better data, CDEC has
conduced two experiments, SUFEX II AND SUPEX III to quantify this suppression
effect. Much progress has been made, but adequate realism does not yet appear
to have been achieved, and the results of thesu two experiments have not been
specifically approved by HQ TRADOC. The techniques which they have developed
may eventually permit the solution of this problem.

. Whet Is not available.

- No completely accepted results on effects of exploding artillery
munitions on dismounted troops.

- No suppression data for exploding small arms (BUSHMASTER) .

- No data on suppressive effects of any types of munitions on mounted

mo red forces.

- No date on suppression effects of any type of munitions on aircraft.

- No data on suppression effects of large caliber direct fire non-

exploding munitions.

If suppression is to be properly evaluated in the assessment of Army

V-A-2

,-jiH — . . '

. .it. J. J -

VJ’ mV. t

forces and systems, a comprehensive program leading to development of necessary
data should be established. Recognizing the significance of the gap, the
initial program could well be quite aggregated and subjective. A progressive
refinement of quantitative information would then occur, with those areas deemed
to have the highest priority receiving the earliest attention and greatest
stress. The remaining portion of this discussion outlines how such a program
might be established and Implemented.

- At figure 1 are a act of parameters needed to initiate the program -
in thla llluatratlon, functiona, distance from FEBA, other variables and degraea
of auppreaaion. Tha parameters may be changed for the final program - these

are for llluatratlon only.

- Tha remainder of the program is based on developing and then filling
in a aet of matrices which described tha suppressive affect on s particular system
in each of the varied conditions of interest . Figure 2 shows such a matrix, baaed
on the parameters identified in figure 1.

- Figure 3 shows the matrix filled out for one sot of parameter! -

in the case for 'the M60A3 tank attacking on a clear day, Tha effects of all types
of fire - direct, indirect and a mix are shown. Since thla is the initial version
of tha matrix, tha aubjectiva aggregated suppression affects shown in flgurs 1
ars used. Experimentation and research may be used to broaden tha categories
(recall that there are 7 In ASARS) and to refine the amount of suppression
suffered under each condition. It appreara that the moat serious effects from
auppreaaion occur in the close-in battle: therefore of the areas on this masting
this la tha one which should racalva primary attention with tha aim of batter
quantifying tha effects of suppression, and in addition quantify tha amount of
degradation in performance associated with a particular suppression affect.

As Indicated in note 7, In the assault suppression may be difficult to daacrlba
or quantify, while it probably does not exist for tha defender.

- Figure 4 expands examination of the MA60A3 tank to a defenseive
posture. Again tha close in battle appears to require the moat attention.

- A "library" of suppression effects for all systems, units, and
functions of Interest In all significant environments should bs dsvelopad in
similar fashion. Figure 3 gives an llluatratlon of tha "books" in tha "library".
Over time thla library ahould be extensive enough to permit consideration of
suppression in all analysis. The library would include tha following steps:

- Development of each "book" baBed on available data plus
subjective evaluation.

- Conduct of research and experimentation to batter quantify
and refine each "book".

- Incorporation of the new data into the appropriate "book".

- Figure aix shows the conclusion of Work Group I. It indicated the
direction to be taken in development of a suppression program.

V-A-3

WORK GROUP X - SUPPRESSION VARIABLES (EFFECTS)

- Following shows Che units on individual functions which will bs
consider sd:

A. Command and control.

B. Target acquisition.

C . Movement .

D. Firepower.

- Battlefield is divided into three bands based on distance from
FEBA, as follows:

Long Range Battle - 2000 to 3000 4- maters.

Close-in Battle - 2000 to 500 meters,

Assault - 500m to FEBA.

- Each weapon system/unlc/or variable will have its own suppression
factors. Examples of variables;

- type weapon or vehicles

- weather

- terrain

- formation

- length of suppression

- Degree of suppression is as follows:

X not applicable.

O no effect.

-1 slight affect.

-2 great effect,

Figure 1,

V-A-4

SUPPRESSION EFFECT LEVELS

WEATHER:

CLEAR DAY

M60A3 TANK CO
ATTACKER

Indirect Dirac t _ _ Mix

Long Range

Battle -
3000+ to 2000M

-2A, -IB, -1C, XD
(buttoned up)

FASCAM 0A,

-IB, -2C,XD

ATGM,-0A,0B,

-1C.XD

Tank X

General Degradation
-2A,-2B,-2C,XD
Synergistic effect
exist but not acct
for

Close in Battle
2000M to

500M

-2A,-1B,-1C,

—ID

(buttoned up)

FASCAM -1A,
-1B.-2C.-ID

ATOM- 1A, -IB,
-1C, -ID

Tanka 0A,0B,
-1C,0D

-2A,-2B,-2C,-2D
Synergistic effect
exist but not accounted
for

0A,0B,0C,0D

NOTES:

1. Minimum kllla of attackar except for FASCAM.

2. Soma casualties to attackar.

3. A significant number of attackers killed considering range.

4. Increasing casualties.

3. Many casualties, but unit Is now willing to take some risks to accomplish
mission.

6. Heavy casualties.

7. While an attacking unit in the assault may not be "suppressed" as discussed
in other areas an attacking unit which is "stopped" or "pinned down" may be
considered to be suppressed. ThiB condition is usually the result of direct fire.

CAPACITY TO BE VOLUNTARILY OR INVOLUNTARILY SUPPRESSED

Figure'' 3.

D.8. HEAVY MAINT
RAIN

Ml 09 BRTY
HEAVY FOG _

M60A3 CO

OLE | -

DEP| M60A3 CO

CLEAR DAY
ATTACK

CONCLUSIONS

1. A matrix of eystems/unita vs. stimuli of significance to combat should be
developed.

2. Each call in the matrix should be expanded into a library of suppression
effects on system/unit functions.

3. Research! test and experiments should be stressed as a program to develop
the quantitative inputs needed by each "book" in the library.

4. Emphasis should be placed on protected systems. Suppression cf these
systems does not seem to have been adequately addressed.

5. For dismounted elements! increased attention should be placed on rear area
combat support and combat service support units.

6. Although suppression la assessed on individuals, the cumulative effect of
suppression of individuals may be a degradation of unit performance which is
synergistic.

7. Duration of suppression must be determined on a unit/individual basis -
continued suppression may permanently degrade Individual, and, therefore,
unit effectiveness.

8. The conditions existing on the assault phaso of combat pressnt different
problems snd may make suppression of leas significance than other phases.

9. Training, manning, and redundancy era essential to reduce the impact of
suppression on unit performance,

10. In asaeesing unit/individual suppression effects, attention must be given
to differences in physical vulnerabilities of craw members, e.g., M109
Chief of Section inside Howitzer vs. Ammo Handler dismounted. (Relate
interaction this factor w/conclusion #6.)

Figure 6.

B. Group II: Suppression Variables (Causes)

Members: Mr. Hardison - Group Leader
Colonel Crawford, TSM Smoke

Lieutenant Colonel Stokes, USA Inst Environ Medicine

Or. Burleson, TRASANA

Mr. Garrett, AMSAA

Mr. Landry, SPC

Mr. Lynch, Boeing Aerospace

Colonel Lemons, TRADOC/USAFAS Representative

Mr. C. R. Holt, Mitre Corp

In order to focus Its effort Group II had the following goals and
questions /Issues :

1. Goals:

a. Identify significant variables

b. Prioritise their Importance

Quest ions/ IssueB :

a. Whet are the critical parameters/slgnatures? (Rate of
flre/volume of fire/weight of ordnance/blast/spaclal variables)

b. What is the suppressive effect of smoke/dust?

c. What are psychological factors?

d. What are physical factors?

c. What are the critical thresholds to trigger suppression?

THE GROUP II REPORT

I ?'

I f

SLIDE 01

SUMMARY

- OUR THINKING FUZZY

- BUT HE ARE THINKING

- WITHIN & BEYOND CHARTER

- PROBABLY REDUNDANT TO OTHERS IN PART

- WE'RE NOT CONVINCED THAT NOTHING CAN BE DONE

- OUR PARTIALLY FORMED IDEAS ARE SHAREABLE.

SLIDE n

WORKING GROUP 2 CONVENTION

SLIDK it 3

PLAINS WHICH WE SUSPECT TO BE IMPORTANT

- SPACIAL - PROXIMITY OF EFFECT TO SUPPRESSEE

- TEMPORAL - NR. OF EFFECTS PER UNIT, TIME DURATION

- MAGNITUDE - SIZE OF THE STIMULI

- EXPERIENCE - HISTORY OF THE SUPPRESSEE

- BEHAVIOR OPTIONS - SHORT TERM RISKS & LONGER TERM RISKS

- PERCEPTION OF WELL-BEINC, AND IT'S DIRECTION OF CHANGE
RATE. (S.S.S.)

SLIDE H

SOME FIRE-INDUCED CAUSES OF SUPPRESSION

LOUD NOISES/BRIGHT FLASHES

— >

INVOLUNTARY REFLEX

BLAST OVERPRFSSURE/ SEISMIC SHOCKS

BODY DISPLACEMENTS

SMOKE/DUST

— >

REDUCE VISION

THERMAL ENERGY /SHELL FRAG

-- >

CONCERN FOR LIFE

DEBRIS, EJECTA

MINOR WOUNDS

CHANGE THINGS, PEOPLE, ENVIRONMENT, ACTIONS

v-b-3

Mil

SLIDE «5

THE CHAIN

ROOT j fftv
CAUSES ^

PHYSICAL

MUNITIONS

INTERMEDIATE

EFFECTS

FINAL

EFFECTS

PHYSICAL CHANGED PERFORMANCE

INVOLUNTARY REFLEX . OF

"LOCALLY RATIONED" 777)\ MAN/MACHINE
DYSFUNCTIONAL SYSTEM

BEHAVIOR

SLIDE H

OUR FAITH IS THAT

- SEVERAL OF THE PRINCIPLE ROOT CAUSES OF SUPPRESSION:

_ ARE OF A PHYSICAL NATURE

_ CAN BE IDENTIFIED AND MEASURED

_ PRODUCE PREDICTABLE/REPRODUCIBLE EFFECTS WHICH

ALTER WHAT ELEMENTS OF FORCES - CAN DO

- DO DO

- A GOOD UNDERSTANDING OF THE ABOVE, EVEN IF NOT ALL
INCLUSIVE, WOULD BE A STEF IN THE RIGHT DIRECTION.

v-a-4

» ■ mwuHmMmwumk* n

. 1iTf - . . *

SLIDE il7

SI, IDE ffi

CAN CONTROL BE SUPPRESSED?

ACQ INFO RE TERRAIN WY, EN OP RAT ,
ENSIT, FRIENDSIT

YES

COMMAND

COMMO

ORGANIZATION

DOCTRINE

TRAINING

YES

V— is— 5

SLIDE #9

CAN MANEUVER BE SUPPRESSED?

CAUSE UNWANTED MOVES YES

(SEEK COVER)

DISSUADE WANTED MOVES YES

CHANGE ROUTES & RATES YES

SLIDE #10

CAN FIRE BE SUPPRESSED?

DIRECT & INDIRECT

YES

POINT & AREA

YES

S-A i S-S

YES

UNARMORED &

YES

ARMORED

LESS YES

HOWITZERS

(NEEDS THOUGHT)

SLIDE 011

SO WHY NOT?

SINCE THE OPNL CONCEPT REQUIRES USE INDIRECT FIRES

- CONTROL

- TO

SUPPRESS

CONTROL

- FIRE

- TO

SUPPRESS

FIRE

- MOVE

- TO

SUPPRESS

MOVEMENT

- SPT

- TO

SUPPRESS

SPT

NOTION; USE FIRES TO COUNTER ENEMIES ABILITIES TO ACCOMPLISH THE SEVERAL
FUNCTIONS, NOT JUST VS MAN UNITS & FS El, MTS.

SLIDE 012

A THOUGHT FRAMEWORK

- F

CONTROL I

FIRE

MOVE

SUPPORT

£ O > U

SLIDE #13

SLIDE #14

_ WE INTUIT THAT _

- WERE OTHER THINGS ABOUT EQUAL, WE WOULD USUALLY PREFER ATTRITION TO
MERE SUPPRESSION, BECAUSE ATTRITION IS MORE LASTING

“ HOWEVER IT SOMETIMES MAY BE FAR MORE POSSIBLE AND LESS EXPENSIVE TO
SUPPRESS THAN TO KILL

- MOREOVER. THOUGH LESS FINAL THAN ATTRITION, SUPPRESSION WILL OCCUR

AND IT STILL MAY CONTRIBUTE GREATLY TO OUTCOMES OF
COMBINED ARMS & SPT OPNS - SO A GOOD BARGAIN AT THE
PRICE (CONSIDERING ALTERNATIVES)

- CONCLUSION t WE NEED TO UNDERSTAND SUPPRESSION

V-E-8

SLIDE />15

IN OUR VIEWS

- SUPPRESSION

CAUSES

ENEMY ACTIONS

- DISSUADE )

- DISRUPTS )

- DEGRADES )

- PRECLUDES )

- SUPPRESSION EFFECTS TEND TO DECAY OVER TIME BUT ARE

RENEWABLE

SLIDE //16

INDIRECT FIRES PRODUCE

- ATTRITION - CHANGES IN THE NUMBER OF ELEMENTS WHICH

CONTINU: TO EXIST IN A FORCE

— AND—

- SUPPRESSION - CHANGES WHAT THE ELEMENTS OF A FORCE:

- CAN DO

- DO

- (IMPORTANT TO KEEP GOOD BOOK ON BOTH)

(MAXIMIZE BENEFIT OF FIRES, CONSIDERING BOTH)

V-n-9

SLIDE 017

_ A RANDOM THOUGHT _

FACT: ARMY SYSTEMS ARE EMBEDDED - e.g. SUB-ITEMS IN ITEMS IN
UNITS IN ORGANIZATIONS IN FORCES.

RESULTS: SUPPRESSION OF A SYSTEM OCCURS WHEN A NEXT LOWER

SYSTEM IS A CASUALTY; CASUALTY OF A SYSTEM PRODUCES
SUPPRESSION OF THE NEXT HIGHER SYSTEM

SLIDE 018

FINALLY

- IT'S ALL MERELY "TERMINAL BALLISTICS"

- WHEN THERE WAS AN ORDNANCE CORP, THERE WERE PEOPLE WHO
KNEW OR WERE LEARNING. THESE THINGS

- BUT NOW .

AD HOC WON'T HACK IT

V-B-10

C. Group III: Data Base Requirements

Members: Dr. Bryson, CDEC - Group Leader
Colonel (Ret) Dupuy, TND
Captain Lawson, DNA
Mr. Cline, SPC

Mrs. Shirley, Infantry School

Mr. Brown, Boeing Aerospace

Colonel Pokorny, TRADOC/USAFAS Representative

Dr. Leake, Armor & Eng Board

Mr. Loveless, USAFAS

In order to focus its effort Group III had the following goals and
questlons/issues :

1. Goals:

a. Data source list

b. Priority of required testing

c. Recommended experimental approach

s. Questions/Issues:

a. What data is available?

b. What are other likely sources?

c. What data gaps remain?

d. What experimentation /tea ting is needed?

e. How should the experiments be designed?

V-C-l

THE WORK GROUP III REPORT

1. What sources of data are available?

There are two prime sources of data available. They are ; 1) historical;

and 2) experimental.

1) A prime source of historical data is British or Operations Research
in Northwest Europe. A team with the 21st Artillery Group accumulated much
data on bombarding German troopa in NW Europe. SLA Marshall held post¬
combat interviews with soldiers in order to get a handle on suppression.

2) For experimental data CDEC has data from the following tests on
suppressiont DUCS, DACTS, SAGE. SUPEX and SUPEX III. The USAARENBD has data
from the Tank Company Night Fight Team and TTS OT II. It will also provide
additional data from the Crewman's Vehicle Reference Header Test which will
occur in the November 1979 timeframe. HEL also has data on the effect of noise
on the ability of a gunner to track a target. Dollord & Miller's, Personality
Theory. McGraw-Hill gives a psychological understanding of fear in terms of the
gradient of avoidance and provides other references.

The results of the experimental data provide insights into the ability of
the suppresses to shoot, move, communicate and acquire targets.

What needs to be done is to connect the experimental darn to the historical
data which is a much greater and ample source.

2. What are other likely sources?

There is a wealth of historical data that naeds to be sorted and organised.

There is also a possibility of additional experiments being conducted to
establish the relevance of this data as well as to fill any gaps that presently
exist.

Some of the sources or other likely sources are;

1) Questionnaires; 2) interviews; 3) police reports; A) FAA pilot reaction
in time and 3) psychological studies of animals under extreme stress.

3. In considering factors affecting suppression (see attached list), it seemed
that three nearly independent, somewhat exhaustive factors were;

1) Type/mlsslon of suppressed unit

2) Immediate relationship of suppressed unit to snemy elements

3) Perceived lethality of suppressive fire

V-C-2

Taken in reverse order, data gaps and experimentation needs are nn follows:
PERCEIVED LETHALITY:

- most date currently available

- need duration of suppression data
IMMEDIATE THREAT

- need data on behavior of suppresses under constant stimulus as a
function of immediate threat of his targets

TYPE UNIT

- need data on differential behavior as a function of whether unit is

— indirect fire unit
— armor unit
— diamounted infantry
—mounted infantry
— other unit

4. Given that a unit la suppressed P(%), what is the degradation of ite
ability to _ _ (aa a function of time)?

- The most important activity to complete the sentence Is "shoot"

“ Except for the interdiction mission, the activities of move,
communicate, and acquire targets are secondary

- Experlmanta are needed to answer this question

NOTE: It proved ueaful to the group to think In terms of tho following
desired reeulta for degrading the enemy force:

1) Damage or disrupt systems

2) Impact on Human Factors
1) Change the Environment

Fire suppression addresses the second item,

V-C-3

FACTORS AFFECTING SUPPRESSION

I. WEAPONS FIRE CHARACTERISTICS!

Volume of Fire Per Unit Time
Cyclic Rate Pet' Burst
Duration of Fire
Acoustic Signature
Acoustic Tone
Accuracy of Firs

Percsivad Lethality of Projectiles

Distance of Passing or Impacting Projectiles from the Soldier
Manner of Distribution1 of Fire

Coordination of Firs with Suppressive Fire from Other Types of Weapons
Weapon's Basic Load
Visual Cuea

Uniqueness of Sound (e.g., ability of enemy to consistently Identify
the sound with a particular weapon)

Actual Lethality of Projectiles

Signature Cues at the Weapon (e.g., muzzle blast)

In Flight Visibility of Projectiles (e.g,, tracer)

Impact Signature (e.g,, debris or dust thrown up by impacting rounds)

Time to Reload

Reliability

Fusing

V-C-4

Primary Determinants:

Proximity of Incoming Rounds to the Individual
Loudness of the Projectile Signature
Volume of Incoming Rounds to the Individual
. Type of Weapons Systems Employed Against the Individual
Unique Projectile or Weapons System Signature

Visual and Auditory Signature Associated with Impact of the Projectile

III. OTHER FACTORS

Experience Under Fire
Leadership of the Unit
Fatigue/Stress

Environmental Factors (climate, weather, terrain, night OPS)

Hunger
Training
Doctrine
Posture
Task Loading
Unit Morale

Level of Unit Casualties
Availability of Cover and Concealment
Distance from Enemy

Croup Dynamics (e.g., social stimuli of other soldiers, NCOs, officers)
Religious values
Mission type

Proximity to Other Unit Members, Commander, Automatic Weapons
Awareness of Enemy Fires

V-C-5

, 'W-fUL ' i* i l< ' J - AAlfcW^ILitk-1

SLIDE m

QUESTION

WHAT IS IT THAT I DO MOT KNOW, THAT I WOULD LIKE
TO KNOW, THAT I CAN FIND OUT FROM:

- ANALYSIS?

- HISTORICAL SOURCES?

- EXPERIMENTATION?

SLIDE #2

TO DEGRADE THE EFFECTIVENESS OF AN ENEMY FORCE,
ONE CAN:

- DAMAGE OR DISRUPT SYSTEMS

- CHANGE ENVIRONMENT

- OTHERWISE ALTER HUMAN BEHAVIOR

V-C-6

SLIDE 03

FACTORS AFFECTING SUPPRESSION

1. TYPE OF UNIT /MISSION OF UNIT

2. PROXIMITY OF ENEMY

3. PERCEIVED LETHALITY

SLIDE 04

HOW DO WE ALLOCATE FIRE

SLIDE #5

GIVEN THAT A UNIT IS SUPPRESSED PI, WHAT IS THE
DEGRADATION OF THAT UNIT'S ABILITY TOs

- SHOOT

- COMMUNICATE

- MOVE

- ACQUIRE TARGETS
AS A FUNCTION OF TIME?

SLIDE #6

SPECIFIC QUESTIONS WHICH MAY BE ANSWERED BY
HISTORICAL OR EXPERIMENTAL DATA

WHAT IS THE NATURE OF SUPPRESSIVE FIRE REQUIRED TO FORCES

A TANX CREW TO BUTTON-UP?

AN ARTILLERY BATTERY TO CEASE FIRE?

AN AD UNIT TO CEASE FIRE?

AN INFANTRY UNIT TO CEASE FIRE?

AN INTERRUPTION OF TARGET ACQUISITION?

AN INTERRUPTION OF COMMUNICATION?

AN INTERRUPTION OF LOGISTICS ACTIVITIES?

V-C-8

slide in

SUMMARY OF ADDITIONAL DATA NEEDED

DURATION OF SUPPRESSION UNDER VARIOUS CONDITIONS

FOR FIXED PERCEIVED LETHALITY, PROBABILITY AND
DURATION OF SUPPRESSION AS A FUNCTION OF:

- ^ TYPE UNIT

- MISSION

- > PROXIMITY OF ENEMY

V-C-9

0. Group IV: Suppression Modeling

Members: Dr. Payne - Group Leader
Colonel Reed, CAC
Captain (P) Wallace, Port Knox
Dr. Dubln , AMSAA
Mr. Glvldan, ARI
Mr. Weiss, Litton
Dr. Blum, Vector Research
Colonel Slater, TRADOC/USAFAS Representative
Mr. Porreca, R&D Associates
Mr. Thorp, TRASANA
Mr. Mlllspaugh, U SAFAS

In order to focus Its effort Group IV had the following goals and
questions/issues :

1 . Goals :

a. Agreement /consensus on the current modeling

b. Agreement on approaches for Improvement

2, Questlons/Isaues:

a. Review current /past methodologies.

b. Review vhat development is on-going.

c. What are the gaps?

d. What approaches are the best now and in the future?

3, Because of the diversity of the manner In which the work of
Group IV was recorded, and In order not to Inadvertently edit out significant
Information, the report of Group IV will be presented in four parts:

a. First day summary

b. Dialogue on the second day

c. Summary presented to Sympoalun participants

d. Chairman's Post - Symposium Summary

V-D-l

The Work Group IV Report; Part a

1. Introduction by Dr. Payne concluded that if we liad reports from Croupe
I and II, modeling would then be a simple process.

2. Our current models have sufficient mathematical flexibility to represent
the small body of data available to us now.

3. Discussion on definitions resulted in essentially the same definition
that was presented in the opening meeting.

4. Discussion on types of models,
a. Models for process control.

Should we create model for this and do we need to determine tactics
or weapons design? Consensus was that we do not want a process
control model.

5. Discussion concerning characteristics of current models which evolved
into discussion of various tactics. Group concluded that suppression
effects are scenario dependent.

6. Discussion of perceived threat/danger versus perceived benefit of action
e.g. volume of fire makes a big difference and casualties in vicinity
spur individual to move. Models that account for effects are efficient
because ws srs not apt to obtain additional data.

Example: We can describe

Flinching

Interfering

Inhibiting

Neutralizing >

Due to equipment choices

position choices

time choices

target choices
reorganization choices

and in anticipation of subsequent action

7. Physical posture of elements in target area affect detection, degrade P
and Pj£ and inhibit ability to shoot or move.

V-D-2

1.3.

i.Lu "e m

aL.u'^i !i * ■ ■- 1 * • ■>» ■ *i r »i k hri

. *1 j acSSfflKa

Alto - suppressing 100X of unit for 50X of the tlms Is sntirsly
different from suppressing 50X of the unit for 100X of the tints. Models
do not always mske the distinction.

8. The discussions of the foregoing topics renged widely end meny diverse
opinions were voiced. However , the group gsnerslly agreed on the following :

a. Suppression la certainly important enough to be modeled.

b. Suppressive effects may ba as important as lethal effects.

c. Suppression is caused by a wide diversity of variables and is difficult
to model explicitly.

d. Generally that which has a greater potential to kill has greater
potential to suppress, with two notable historical exceptions, white phosphorus
and the "Headlight" round for WW11 bombers.

s. Artillery bombardment almost completely eliminates return fire by
Infantry from the beaten tone.

f. Artillery will probably cause tanks to button up and move out.

The Work Group IV Report: Part b

On the morning of the second day (third session) a portion of the
dlaeueelon wee recorded in writing; and, simultaneously, the names of the
primary participants were given. Their names appear below followed by the
dialogue:

GEN

(Ret) William Depuy

Dr.

Robert Blum

Dr.

Henry Dubin

Dr.

Wilbur Payne

COL

Robert Reed

Mr.

Keith Thorp

V-U-4

Dialogue

Depuy: Historical perapectiva on suppression. US failure to grapple with the
real problem - that la gattlng fire on the target when the ground
attach begins. When the suppression Is needed mat - all fire ceases.
This Is one thing modeling does not address sufficiently. At Monts
Casino the Germans had 3-5 min after British prap ended to get into

position.

Payne: Models have the capability. The problem exists with the tsctlcal
approach taken by the player a/programs.

Perhaps we need to deal with activities and consequences of activi¬
ties dealing with exploitation of suppression.

Depuy: The Carmans prepped with small amounts of artillery , then heavy weapon
direct fire, and finally with small arms - suppression. US approach
was heavy artillery - lull - then attack (large groups of targets).
Israelles will not attack with their tanks until they have destroyed
all visual enemy tanks or suppressed or driven them off. Can models
reflect that?

Payne: Yea — it depends on tha scenario presented by armor typas. One of
the problems is modeling the time after suppression. The Russians'
model lntlial go to ground time then all the rest is reorganisation
time.

Depuy: Difference exists betvasn prepared position and hasty position
reaction to suppression.

Depuy: Historical perspective on suppression. US failure to grapple with the
rati problem - that Is getting fire on the target when the ground
attack begins. When the suppression is needed most - all fire teases .
This it one thing modeling does not address sufficiently. At Monte
Casino the Germans had 3-5 min after British prep ended to get into
position.

Payne: Models have the capability. The problem exists with the tactical
approach taken by the players/ programs.

Perhaps we need to deal with activities and consequences of activi¬
ties dealing with exploitation of suppression.

Dapuy: The Carmans preppad with small amounts of artillery, then heavy weapon
direct fire, and finally with small arms - suppression. US approach
waa heavy artillery - lull - then attack (large groups of targets).
Israelite will not attack with their tanks until they have destroyed
all visual enemy tanka or suppressed or driven them off. Can models
reflect that?

Payne: Yea — it depends on the scenario presented by srmor types. One of
the problems is modeling the time after suppression. The Russians'
model intilal go to ground time then ell the rest is reorganization
time.

Depuy: Difference exists between prepared position and hasty position
reaction to suppression.

V-D-6

Payne)

Dubln:

Payne:

Dapuy:

Payne:

Dubln;

Read)

Thorp:

Payna:

Thorp:

Payna:

Reed:

Payna:

Modela do handle thla although perhaps Incorrectly. Going beyond
thia nay cauaa uaera to look too closely at details. The correla¬
tion axlats between lethality and auppresslvenese. It nay lead
to problems to compensate for the variations to that rule.

What General Depuy may be telling us la that we do not address
the tactics of suppression.

Again this is a function of the tacticians using the models.

Modela ahould also handle performance of crews.

People are not comfortable with projections of lees than outstanding
performance. Any model is capable of doing this.

The biggest criticism in our last games is that there is too much
attrition for rounds expended.

Models need to better address how much degradation resulta.

Models need to address continued suppression. Tlmss/Amount Anno.
8ome models do that (ASSARS, etc.)

Is allowing .hat capability worthwhile?

Transition states arc Infrequent.

General Dupuy may be looking for a process control model to explore
tectlcs.

Every means of enhancing suppressive effects, degrades lethal

V-D-7

effects. Suggest two level board to review proposals - one to
review tffsets, one to decide If It Is cost effective. Models can't
answer that question.

Payne: Almost any round will produce flinch. Bigger rounds produce longer
effects. Models don't represent neutralization (from long duration,
saturation explosives).

Reed: Whet about Nukes! Delays casualties, unit dissolution, suppression

on grand scale.

Dubln: Chemical weapons also?

Reed; Psycho/Phyelo effects - heat Injury?

Peyna: We have difficulty Isolating suppression. Different resultB from
proving ground end combat involve many factors. May be double-
dipping In trying to solve this problem.

Dubin: Greet deal of bureaucratic pressure to reduce rate of attrition,
end speed. Suppression Is a straw we are grasping for.

Payne: Will use suppression to label effects which we cannot effectively

factor. Our models ere throughput models - if you put It in at one
and, they come out et the other.

Blum: Models do not Include conditioning variables.

Peyne: 1 feel it ie better with the current system. Player inputs behavior.

Blum: Agree.

V-D-8

Ues as a surrogate to conditioning variables (state variables).

The Inputs of the players.

Conditioning Variables for Suppression:

1 . Backgrounds

a. Audio

b. Visual

c. Duration

2. Command and Control Function

3. Conditioning variables for aggregated models.

Payne: We have not ansvered the question raised by Dr. Dubln with regard
to model pace VS battle pace.

SUMMARY - This session was spent discussing the need for suppression
modeling, problems Involved and capabilities of existing models to In¬
corporate both differing tactics and euppreaalve effects.

The military needs for suppression were provided in large part
by General (Rat) Depuy through discussion of WWII experience and Zaraall
use of suppressive end lethal fire prior to armored attacks. His questions
to the group were primarily of the model's capabilities to examine these
tactics and effects.

Answers to his questions were given primarily by Dr. Payne who
stated that Depuy' s desires could be met with existing models by proper use
of tactical decisions and salectlon of scenarios to be played.

Most of the problems surfaced during this session dealt with
difficulty in obtaining data and the degree of detail that should be In¬
corporated into the models.

V-D-9

A driving problem from AMSAA's viewpoint is the need to provide
effects lntemel to the models that reduce rate of attrition and speed of
the battle. It is their experience that almost all games progress at
speeds end attrition rates much higher than real life based on history.

Questions were posed regarding the inclusion of suppression in
models of nuclear games such as DIVWAG at Sandia Labs. No conclusions
regarding this were reached.

The group adjourned at 1000 hours arriving at the same con¬
clusions reached the previous afternoon.

V-D-10

Slide #1

QUESTIONS AND ISSUES

1. Review current/peet methodologies.

2. Review whet development le ongoing.

3. Whet ere the geps?

4. Whet epproeehea ere the beat now end In the future?

Slide 12

MODEL TYPES

1. Modela that account for effecte.

2. Model! for procese control:
e. Tactlca *
b. Weapon dealgn

MODELING APPROACHES

1. Hypothesise a particular action in reaponae to riek, predict effect on
perf onrance .

2. Predict affect on performance with no apecif lcatlon of action.

Slide #3

CURRENT/PAST METHODOLOGIES

- Alnoat all are attempts to account for effecte, predict performance
without apecif ylng action.

- Can build and occasionally use modal approach 2.

V-D-ll

Slide U

WORKING CROUP 2

CONVENTION

| NOT THIS

ATTRITION

S' ^
CASUALTIES

A N

SUPPRESSION

SUPPRfi

SJ^ION

[CASUAL-\

HIES /

PERF ,

\Ay

IN THE SMALL

Slide 15

IN THE LARGE

Flinching

Equipment choices

Interfering

Positioning choices

Inhibiting

Time choices

Neutralising

Target choices

Due to -

Reorganization choices

V-D-12

in anticipation of -

The Work Group IV Report: Part d

SUPPRESSION MODELING

Summary of Discussion in Working Group IV

1. The initial discussion centered on fundamentally different types of
models. That is models that differ in purpose or in the type of problem
to be investigated. In the terms used by the working group these were
described as Models for Process Control and Models for Representing
Suppressive Effects*

a. Models for Process Control.

(1) This term was used to describe models that might be used either
for weapon system design trade-off purposes or perhaps for qualitative re¬
quirements purposes.

(2) For example, it is possible that specific design fsaturea of
weapons or munitions could enhance their suppressive effect. If there were
reseon to believe this and if such features could be added with neither
penalty in the lethal affects or added cost, there would, of course, be no
need for either model or analysis. However, the perversity of nature makes
it almost certain that, even if we knew how to design weapons with assurance
that their suppressive effect would be enhanced, we would face tradeoffs of
lethal ef facte or incraaeas in cost.

(3) There is some evidence in or on the fringes of history
that suggest that suppressive effects may not be directly and tightly

V-D-13

coupled with lethal effect. Further, there are some suggestions that
weapons with a high suppressive potential might yield greater benefit
In some uses than more lethal weapons with lower suppression potential.

(a) Cases of this that were cited as probable evidence from
history Included the steady Increase In the use of White Phosphorous
In final protective fire during WW II. This has generally been ex¬
plained In terms of the suppreslve benefits of the smoke and of an

apparently deep seated fear of burning. The Headlight round (a .50
caliber round used In B-17's that was modified so the tracer was highly
visible to the target) was also discussed. It was noted that some
people attribute the universal trend toward automatic rifles as an
example. There Is some reason to believe that automatic rifles will
In fact and predictably produce fewer casualties than aimed fire from
semiautomatic rifles. But there Is also some evidence that units
armed with semiautomatic rifles are less likely to engage when faced
with automatic fire.

(b) It Is clear In the literature that some people believe
that mixes of bomblets and mines or of instant and delayed fuzed
bomblets would have more total effect than would rounds that contain
only Instant fuzes even though current models show these would have lower
expected lethal effect than the same weight of Instant fuzed bomblets.

(4) In the end, perhaps because the composition of the group
did not Include weapon design engineers, there was an apparent con¬
sensus that there was little Interest In models of process control.

V-D-14

Even those members Mho t.iought such models would be useful If available
did not see a clear path to their development. That Is, neither further
review of history nor feasible peacetime experiments are likely to
produce a semi quantitative basis for relating particular design features
to specific enhancements of suppressive effect.

(5) If these views are correct then a model that purported to
be a process control model would, In the end, rest on assumptions that
connect cause and effect, and would not be different from models de¬
signed solely to represent effects.

(6) If there Is management Interes. In this class of problems,
they could be approached, In the absence of process control models, In

a more direct If judgmental manner. For example, a board could be
created to review specific weapon design proposals. If this board
judged the specific proposal would produce some enhanced suppressive
effect a second board could explore and render judgment on whether the
benefit achieved from this would outweigh the penalty In lethal effects
or costs. If either board could hypothesize the suppression enhance-

ment In specific terms this could, of course, be Investigated In models
designed to represent effects. As CG TRADOC, GEN OePuy Initiated the most
recent round of renewed Interest In suppression through the SUPEX experiments.
His discussion with the group Indicated his interest was to make sure that
the effects of suppression were not ignored.

b. Models for Representing Effects.

(I) The group generally agreed that In addition to their
potential to kill and damage, weapons do indeed have less direct effects
embodied In the working definition of suppression. Further, these effects
are generally too large to Ignore and in many cases may be asj or more
Important In combat than the damage producing effects. Because of this
and In spite of our limited historical or empirical knowledge, there was
general agreement that the effects should not be ignored in models of
combat.

(2) It was clear patUy from the briefings in the general
session and partly from the knowledge of members of Working Group IV
that the most detailed of the current family of combat models have an
elaborate and flexible representation of suppressive effects. Even
the analytical and rather abstract models can represent assumptions
about suppressive effects. At the least, rates of target detection and of
fire are explicit or Implicit Inputs to most models and these can be
Judiciously chosen to represent whatever the user believes about
suppression.

(3) The present models seem able to represent the suppressive
effects of fire as these are described In both historical and empirical
sources. They do not, however, usually represent all of the potential
effects In their day-to-day use In various studies.

V-D-16

(a) Generally speaking, the current Monte Carlo models
accumulate Information over time about the number and type of rounds
landing In the vicinity of combat elements. If the element Is not
killed by the fire the models then associate a change In posture and/
or of activity of the element as the suppressive effect. In particular
an element may disappear as a direct fire target and may simultaneously
have reduced capability both as a detector of targets and In firing
on them.

(b) In most such models the different types of arriving
rounds have different weights or suppression Indices. Similarly, to
one degree or another, It Is generally true that the suppressive effect
of close misses Is greater than more distant ones.

(4) These are not the only "suppressive" effects that are or
can be represented In current models.

(a) The working definition of suppression proposed In the
general session would Include the effects of smoke and dust In so far
as they affect vision or coordination as "suppressive" effects. There
Is a large experimental program covering at least the vision related
effects of smoke and dust. The present models are rapidly changing

to exploit the results of this Investigation.

(b) The group hypothesized and named several different
effects that might represent a subdivision of the broad phenomenon
Into sub classes. These were classified Into two different categories.

V-D-17

i.—. i-flfct javw .

<ii. 4. JlL .LU.ii.':

I Actions taken as a result of receiving fire.

a Flinching. A term used to describe a largely Involuntary,
Instantaneous reaction to the noise or flash of a round. Generally
believed to be of short duration this can nevertheless Interfere with
Immediate on going tasks such as aiming or controlling weapons. This
Is not usually represented as a separate phenomenon In combat models.

b Inhibiting. A term used to describe a more or less con¬
scious and controlled action to reduce exposure to a risk from fire.

This term was used for actions such as taking cover or changing the
state of movement. To varying degrees present models represent this.

c Neutralizing. This term was used to represent what
appears as a very long term psychological effect of fire. The prin¬
cipal historical source for this Is the final report of Operational
Research Section 2. But there are other historical examples that
Indicate It is a real phenomenon. It Is not represented in current, small
unit combat models. The volume-duration dimensions of fire that occurs In
such models seldom, If ever, reaches the range in which this phenomenon
seems to occur.

d Interfering. This term was used to represent effects where,
Independent of psychological state, the effects of the fire would make It
Impossible to continue or perform some task. This subset would then In¬
clude effects of smoke or dust. Current models do not usually Incorporate
these effects In that part of the model called the "suppression" submodel.

V-D-18

2 Actions taken In anticipation of fire.

a It seemed worthwhile to note that even though these are
not usually described as "suppressive" effects there are some Influences
from the threat of fire that are at least Implicitly represented In
current models. For example, the threat of fire Influences the choice
of positions for elements In the scenario. It also Influences the

timing of certain events In the sense that a unit may be Instructed
not to occupy some position until after the preparatory fire phase.

On a larger scale It can result In limits on resupply or support
operations, for example, through a doctrine that permits supply operations
only at night. It Is, at least partly, anticipation of fire that leads to
some equipment choices such as the APC and SP artillery.

b These effects are represented both In the Input and output
to present models. For example, to the extent certain otherwise desir¬
able fighting positions are not occupied, both casualty production and
casualty acceptance are affected In current models.

2. A purist might note that the difference between the two types of
model 1$ superficial. The principal sources of quantitative data for
either class of models are the Final Report of ORS-2, a source that
under' les early US and present UK models, some work by Litton using
sources and data from Vietnam and the Series of SUPEX experiments at
CDEC. As a general observation all of these Indicate (or at least
do not conflict with the hypothesis) that, In the main, the suppressive
effect of a given round at a given distance Is closely correlated with
Its lethal potential. That Is, considering the Individual effects of

V-D-19

single rounds, a round with greater potential for casualty production
also has greater suppressive potential. This may not be universally
true and, as noted, there are some examples of probable exceptions. This
relation between lethal and suppressive effect might be perfectly adequate
as In present models to capture most of the effect of suppression. But so
long as the exceptions remain unexplored and unexplained, it would be wrong
to use the results of these for detailed weapon design purposes. It could
be equally wrong, without Intervening judgment, to use the results of these
models for choice of tactics.

3. Generally speaking, the working group had no specific suggestions

for modifying the basic structure of the best of the current combat
model s.

a. In every area where there Is a modicum of data the models can
and do use It.

b. In areas where there Is nearly complete absence of data the
models can accept Judgmental Inputs. Among such areas, It can be noted
that wide differences exist In the literature and In present models or In
their application about the rate of recovery from the flinching and
Inhibiting subclasses of suppression. Nor is It clear that present models
distinguish between "flinching" and "Inhibiting" effects If, Indeed, there
Is a difference. It can also be noted that wide differences exist about
suppression effects on the crews of armored vehicles and artillery units.
None of the three basic sources of data deal very directly with armored and

V-D-20

artillery units. It can be shown that the computed results from the present
models depend as much on assumptions about the duration of suppression as
they do on the probability that It occurs.

c. It might be possible to narrow these differences either by
bureaucratic flat or by emerging consensus. But. In the main, It Is
very clear that most differences In the modeling of suppression rest on
a quite real difference of opinion about the effects. Since that
difference exists It Is probably more useful to Insist that the particular
treatment of suppression be a mandatory part of study reports than It would
be to Impose a single standard approach to this problem.

E. Croup V: Supprasslon/Countersuppresslon Combat und Training Developments

Members : Mr. Murphy, SAI - Croup Leadar
Major Graham, Infantry School
Major Money, Fort Rucker
Captain Gunderson, AMSAA
Lieutenant Colonel Bacon, TSM Smoke
Colonel Quinlan, TRADOC/USAFAS Representative
Major Johnston, Fort Bliss
Major Kalla, AMSAA

In order to focus its effort Group V had the following goals and
questlone/laeuee i

1. Coale:

a. Prioritise on-going developments

b. Recommend high pay-off areas

2. Queetione/Issuee:

a. What combat activities are most easily suppressed?

b. What combat activities offer best pay-off for suppression?

c. How do we become less suppressible? (tactics, material, training)

d. How do we become better suppreBBors? (tactics, techniques,
muni t lone, weapons)

V-E-l

The Croup V Report

DISCUSSION:

- Th« definition of suppraasion may be adequate but the group Is still
examining what it mesne to 'suppress.' Suppression is ona of the things we
do to defeat the enemy. In order of increasing severity we do the following
disrupt, suppvess, neutralise, destroy.

- Emphasis should be placed on the training of our troops to make them
harder to auppreas and to make them better suppressors, particularly in a
chemical warfsre/smoke environment.

QUEST IOHS/ISSUBS i

What combat activities are most easily suppressed?

- exposed pereonnel

- soft equipment

- vulnerable equipment + lack of training - easily suppressed target
What combat activities offer beat pay-off for suppression?

- focus on front line units/activities

- timeliness

- armor, observation, C&C, fire support, ADA
How do we become less suppresslble?

- position/equipment hardening

- shoot aod scoot

- training/an understanding of deception

- laser considerations

How do we become better suppressors?

- better, more realistic training

- timeliness

- examine munition mixes, e.g., FASCAM 4 ICM

- training (combined arms, in degraded environment)

- BEAD: integrate efforts of USAF and Army air and ground assets

V-E-2

■ uiiiw.ij... . i. *■ •na.wnmaimias

GOALS;

Prioritize ongoing developments:

- GSRS . FASCAM*

- BUSHMASTER - IFV/CFV

- IMPROVED SMOKE* - DAD-C3

- FIREFINDER

* - Priority

- RPV

- TACFIRE/BCS

- ARP

- COPPERHEAD

- HELF1RE

- ARTY PIP'S*

- SINCGARS
-OTHERS?

Recommended high pey-off areas
- maneuver

- Fire Support

{

SUMMARY

"Suppression" requires definition end clerif lcetlon through
measurement. The elms dimension is Important.

Training offers lcvsrsge In Improving our cspabillty to suppress
and to become less suppressable.

Appropriate munitions mixes have not been determined, nor ere the
Implications of smoke and other forms of observation available for consider¬
ation by combat developers.

The dimension of suppression should be considered along with
lethality In prioritising hardware under combat development. While the
priority may not change, the mix, doctrine, and tactics of systems will be
Influenced whan this Is placed Into perspective. Emphasis should be on
product Improvements for the currant time frame.

SECTION VI - ADDITIONAL MATERIAL

The articles in this section were submitted for consideration at the Fire
Suppression Symposium, but only one article was submitted in a sufficient
quantity to allow each participant to receive a copy; therefore, the
seven articles are Inclosed here for future consideration in studying the
suppressive effects of fires on the battlefield. The titles of the articles
and the namea of their authors appear below.

Appendix A

Appendix B
Appendix C
Appendix D

Appendix E

Appendix F

Appendix G

A Further Look at the Prediction of Weapons Effectiveness
in Suppressive Fire by Albert L. Kubala and William

L. Warnick (ARI)

Executive Summary of SUPEX TUB Final Report (USACDEC)

Indirect Fire Suppression Model by Phillip M. Allen (AMSAA)

Review and Evaluation of Current Suppression Models With
Proposal for Interim Model by Phillip M. Allen (AMSAA)

Suppressive Effects of Artillery Fire by F.W. Niedenfuhr
(MITRE Corporation for DARCOM)

Toward a Theory of Suppression by HERO Staff (Historical
Evaluation and Research Organization, a subsidiary of
T.N. Dupuy Associates)

Weapons Effectiveness and Suppressive Fire by George

M. Gividen (ARI)

ARI TECHNICAL REPORT
TR-79-A19

A Further. Look at the Prediction of Weapons

Effectiveness in Suppressive Fire

Albert L. Kubala and William L. Warnick
HUMAN RESOURCES RESEARCH ORGANIZATION
300 North Washington Street
Alexandria, Virginia 22314

MAY 1979

Contract DAHC 1 9 -75 -C-0025

Monitored by

ARI Field Unit at Fort Hoot', Texas

Prepared far

U.S. ARMY RESEARCH INSTITUTE

fer tbe BEHAVIORAL eed SOCIAL SCIENCES

S001 Elseakewer Arenas

Alexandria, Virginia 22333

u. S. ARMY RESEARCH INSTITUTE

FOR THE BEHAVIORAL AND SOCIAL SCIENCES

A Field Operating Agency under the Jurisdiction of the
Deputy Chief of Staff for Personnel

WILLIAM L, HAUSER

JOSEPH ZEIDNER
Technical Director

Colonel, US Army
Commander

Reiearch accompl lifted

under contract to tfte Department of the Army

Human Rtaourcea Reiearch Organization

N0TIC8S

DISTRIBUTION: Primary dlltrlbutlon of thu raport nil baan madt by ARI. Hum addraii eorrttpondanea
oonoarnlnj dittWbutlo" of raporta to U. 8. Army Raaiarch Innuuta for tha Bthavioral and Social Seiancat,
ATTN. reai-P, 8001 Biaanhowar Avanua, Almindrii, Virginia 22333

PINAL PltaQaiTlQN: Thl» raport miy bl dattroyad yyhan it ii no loogar naadad. Plum do not rityrn it to
th* U. t. Army Riaaareh Initltuti for th* Blhivioril »nd loclil Scnneai.

NprH: The finding! in thu ripen • r» not to b« eonnruid il in offlclil Dapartmant of th* Army pontion.
unlan M daaignatad by oth»r authoruad doaumanta.

I. nuBRK

ncruR i wwuncn i a i iun rAUE

BBFORE COMPLBTWO gOgjj

I RECIPIENT'! CATALOQ NUMBER

I. OOVT ACCESSION NO

TR-79-A14

4. TITLE rand SuAlttl*; I

A FURTHER LOOK AT THE PREDICTION OF WEAPONS
EFFECTIVENESS IN SUPPRESSIVE FIRE T

AUTHOR**}

TYRE OR REPORT A RERIOO COVERED

Technical Report

11 May 1977 - 11 May 1978

RERRORMINO ORO. RCRORT NUMBER

FR-WD-TX-78-4
contract or oAant HUMBER**)

Albert L. Kubala and William L. Warnick

DAHC 19-75-C-0025

I. RERRORMINO ORO AHI I ATIOR NAME AND ADOREIt

Human Resources Research Organization
300 North Washington Street
Alexandria, Virginia 22314

n. CONTROLLINO ORRICE NAME ANO AOORBU

,0' ISISVSoV^SIVVu^WrV' ta,k

2Q763743A775

It. RBRORT DATE

HQ TCATA

Fort Hood, Texas 76544

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US Army Research Institute for the Behavioral and
Social Sciences

5001 Eisenhower Avenue, Alexandria, VA 22333

May 1979 _

II. NUMBER OR RAO El

IT security class. (•/ an* m»mo

Unclassified

TIT- ATr5M785lN'WXBrNa'

la. exifkieuTioN bTXTImInt *•* SSS KSfOi)

Approved for public release; distribution unlimited.

17. OIITRieUTION St ATIMENT <•! St* (tiMil Ml *r*l In MUt* M, II If/teni i» h « ft*R*rt)

Tl. IURRL BNENT ART HOTEI

Monitored by Charles 0. Nystrom, ARI Field Unit at Fort Hood, Texas

II. REV WORD! fCmtinu* on *1S* If na«**tar R Ml IlMlIfy A y kloak mmkmt)

Suppression

Small Arms Effectiveness

It A SI TRACT rCMUMlII RRMTMRR «M j? mmiNf Ml IHMfllR Ay iiiii mw>Rj

This research and literature review investigated the relationship between
acoustic signatures of small-arms projectiles and the suppressive behavior which
reaults from soldiers' perceptions of danger. Kinetic endrgy, which is
associated with perceived loudness of passing projectiles, appears to bo the
primary physical property of projectiles that affects behavior under fire. The
report la written for military personnel.

DO,ja2w 1473 edition or ♦ mov •» n obsolete Unclassified

security clash rication or mis rase *ihan bar* Kit**)

Army Project Number
20763743A775

Human Performance
in Field Assessment
Contract DAHC 19-75-C-0025

Technics! Report TR-79-A19

A FURTHER LOOK AT THE PREDICTION OP WEAPONS EFFECTIVENESS
IN SUPPRESSIVE FIRE

Albert L. Kubals end William L. Warnick
Human Resources Research Organisation

Submitted by:

George N. Gividen, Chief
ARI FIELD UNIT AT FORT HOOD, TEXAS

May 1979

Approved by:

Frank J. Harris, Acting Director
Organizations and Systems
Research Laboratory

Joseph Zeidner, Technical Director
U.S. Army Research Institute for
the Behavioral and Social Sciences

Approved for public release; distribution unlimited

FOREWORD

The Fort Hood Field Unit of the Army Research Institute for the
Behavioral and Social Sciences (ARI) provides support to Headquarters,
TCATA (TRADOC Combined Arms Test Activity; formerly called MASSTER—
Modern Army Selected Systems Test Evaluation and Review). Thia support
is provided by assessing human performance aspects in field evaluations
of man/weapons systems.

A war using modern weapons systems is likely to be both Intense end
short. US man/weapons systems must be effective enough, immediately, to
offset greater numbers of an enemy. Cost-effective procurement of
improved or new combat systems requires testing that Includes evaluation
of the systems in operational settings similar to those in which the
systems are Intended to be used, with troops representative of those who
would be using the systems in combat. The doctrine, tactics, and train¬
ing packages associated with the systems being evaluated must themselves
also be tested and refined as necessary.

This report presents the results of an investigation originally
designed to determine what aspects of the auditory signatures of passing
projectiles are perceived as making the projectiles dangerous, resulting
in suppressed behaviors. The report presents a review of the relevant
literature, and examines kinetic energy as the primary physical property
of projectiles that affect behavior.

ARI rasearch in this area is conducted as an in-house effort, and
as joint efforts with organizations possessing unique capabilities for
human factors research. The research described in this report wee done
by personnel of the Human Resources Research Organization (HumRRO),
under contract DAHC19-75-C-0023, monitored by personnel from the ARI
Fort Hood Field Unit. This research is responsive to the special re¬
quirements of TCATA and the objectives of RDTE Project 2Q763743A775,
"Human Performance in Field Assessment," FY 1978 Work Program.

A FURTHER LOOK AT THE PREDICTION OF WEAPONS EFFECTIVENESS IN SUPPRESSIVE

FIRE

BRIEF

Requirement:

The work carried out In this study is that referred to In paragraph
2,2.23 of ths Statsnent of Work dated 16 May 1977 under the title of
"Suppression Research." The objectives of this effort were:

• To provide a review of the literature published since 1970 on
fire suppression by small arms.

* To determine from information available what aspects of the
acoustic signatures of projectiles contribute to their being
perceived as dangerous and result in suppressed behaviors.

Procedure :

A field study conducted in the early 1970b produced a psychological
rating of "perceived dangerousness" of a series of small arms fire
events. A behaviorally anchored Suppression Index (SI) was sIbo derived
from a similar set of small arms fire events. It was concluded that the
psychological scalss ware baaed almost solely on the subjects's reac¬
tions to ths noises of the passing projectiles. However, no data on the
acoustic signatures of the projectiles were obtained at that time. This
effort was initiated aB a literature review to determine whether data on
acoustic signatures of the weapons employed were available, and if so,
whether any aspect (e) of these signatures could be employed to "predict"
the psychological scales. A review of the general literature on sup¬
pression was also conducted.

Principal Findings:

• Data on the acoustic signatures of projectiles down range
from the weapon are extremely limited, and are not complete
enough to be of any value in determining the relationship
between signatures and the psychologically-derived Suppression
Index and perceived daugerouaness ratings.

• Kinetic energy, which is believed to be closely related to the
perceived loudness of passing projectiles, appears to account
for nearly 100% of the variance between weapons on both the
Suppression Index and the perceived dangerousness ratings.

• Further research is needed to validate the findings relative
to kinetic energy, and to better establish the mathematical
relationship between miss distance, rate of Fire, and psycho¬
logical scales such as the Suppression Index.

V I

Utilization of Finding*:

Operations research analysts in attempting to piay suppt«“ijn la
combat models have had to rely on intuition and fragmentary description*
of behavior under fire to develop their models. As a result, the I han
dling of auppraesion haa been highly variable. The ®

analysis in thia research should provide them with another tool to help
refine computer Models involving auppreaeion play.

vli

CONTENTS

CHAPTER PACE

1 Background . 1-1

2 Research Problem and Literature Review . 2-1

Discussion of the Literature . 2-5

Interview and questionnaire studies . 2-6

Experimental studies . 2-8

Models . 2-12

3 Analysis . . . . 3-1

4 Recap, ituation and Recommendations ... . 4-1

REFERENCES . R-l

FIGURES

■1

2- 1 Probability of suppression as a function of radial miss

distance . . . 2-10

3- 1 Perceived dangerousness as a function of kinetic energy

(adapted from Kushnick and Duffy) . . . 3-6

TA'ILES

2-1 Response Alternatives to Fire Events . 2-2

2-2 Suppression Scale Scores . . . 2-4

2-3 Relationship Between Kinetic Energy (KE) and Perceived

Dangerousness . . 2-4

2- 4 Most Feared United Nations Weapons. . 2-7

3- 1 Relationship Between Projectile Diameter, KE, and

Perceived Dangerousness . 3-5

3-2 Computed and Actual Perceived Uangerouaness Ratings Based on

Kinetic Energy. . . 3-8

Chapter 1
BACKGROUND

It has long been believed that most weapons, in addition to their
casualty-producing capabilities, also have Incapacitating psychological
effects which may inaccurately reflect the actual threat. Earlier works
dealing with these psychological ef fecte^' ** ’•* 5 invoked the concept of

fear. Essentially, all of these efforts were directed toward finding
out which weapons were most feared by the respondents. Subjects queried
included American, British, German, North Korean, and Communist Chinese
soldiers. While these works did demonstrate that fear of a weapon and
Its casualty-producing capability were not perfectly correlated, only
minimal Information was obtained on the reasons for the observed dis¬
crepancies. Furthermore, as Terry® pointed out, the data obtained were
strictly ordinal In nature with the scales typically ranging from most
feared to least feared. In addition, the effects on the actual behavior
of the Individuals queried were not determined. In other words, it
could not be determined whether these stated fears had any effect on the
conduct or the outcome of a battle. Therefore, these earlier data ara
useful only as an aid In the formulation of hypotheses.

One of the behavioral results expected from fear of enemy weapona
Is the phenomenon called "suppression.'' The term suppression has long
been a part of the Army's vocabulary. However, attempts to arrive at a
precise definition have proven elusive.'7 Virtually all definitions of

3J. Dollard. Fear in Battle , The Institute of Human Relations,

Yale University, New Haven, Connecticut, 1943.

H. Goldhamer, A. L. George, and E. W. Schnltzar. Studies of
Prisoner-of-War Opinions on Weapons Effeotiveneaa (Korea) (U) , RM-733,
Rand Corporation, Santa Monica, California, December 1951.

L. A. Kahn. A Preliminary Investigation of Chinese and North
Korean Soldier Reaotions to UN Weapons in the Korean War, ORO-T-14
(FEC) , Johns HopkinB University, 1952.

4l. A. Kahn. A Study of Ineffective Soldier Performanoe Under
Fire in Korea, ORO-T-62 (AFFE) , Johns Hopkins University, 1954.

6S. A. Stouffer, et al. The American Soldier: Combat and Its
Aftermath , Vol II, Princeton, New Jersey: Princeton, University
Press, 1949.

R. A. Terry, Toward a Psychological Index of Weapons Effective¬
ness, Part I: Field Studies, Technical Report 1419-5, University of
Oklahoma Research Institute, Norman, December 1964,

L. A. Huggins, Jr, "A Simplified Model for the Suppressive Effects
of Small Arms Fire," MaBtera Thesis, Naval Postgraduate School, Monterey,
Cn I I Torn I , September 1971.

l-l

suppression attempt to relate the volume of fire of one force to a
degradation of performance of the opposing force. Tor example, Winter
and Clovis" define suppression as "...the causing of human reactions
that reduce individuel (unit) efficiency to fire, observe, and move,"

A Combat Developments Experimentation Command (CDEC) report^ states that
the TRADOC definition is "the degradation of specified combat activity
for a particular period of time." According to Kinney,^ "suppression
ie e short-term transient degradation in the combat performance of
infantryman. It is produced by their behavioral response to the le¬
thality potential (risk) of impacting weapons that do not incapacitate
them." The Ad Hoc Group on Fire Suppression^ states that suppression
Is:

...a process which causes temporary changes in
performance capabilities of the suppressee from
those expected when functioning in an environment
which he knows to be passive. These changes are
caused by signals from delivered fire or the threat
of delivered fire, and they result from behaviors
that are intended to lessen risk to the suppressee.

jj Numerous other definitions have been given in the literature, but all of

s' those located ware very similar to the preceding examples. All of the

definitions imply that suppression is temporary, i.e., it is not a
jr result of physical incapacitation due to injury or death. They also

imply that some aspect of performance must be adversely affected before
| a force or an individual can be said to be suppressed. The performances

f most frequently mentioned are those of observation, returning fire, and

k maneuvering. However, a broader view was taken by the Ad Hoc Group,

R. P. Winter and E. R. Clovis. Relatione hip of Supporting Weapon
Systems Performance Charade notice to Suppression of Individuate and

Small Unite, TR 73/002, Defense Sciences Laboratories, Mellonics Systems
Development Division, Litton Systems, Inc., Sunnyvale, California,
January 1973.

Project Team II, US Army Combat Developments Experimentation Com¬
mand, and Braddock, Dunn, and McDonald Scientific Support Laboratory,
Fort Old, California. Diapereion Against Concealed Targets (DACTS),
USACDEC Experiment FC 023, Final Report, July 1975.

D. G. Kinney. Suppression Analysis Technique (U) , unclassified
version of paper presented to 33 MORS, Weapons Planning Group, Naval
Weapons Center, China Lake, California, undated.

!■ 11

!> US Department of the Army, Office of the Deputy Chief of Staff

■ For Research, Development, and Acquisition, Washington, D.C. Report

f of the Amy Scientific Advisory Panel Ad Hoc Croup on Fire Suppression,

( ODCSRDA Form 11, 7 July 1975.

For example, they spoke of the suppression of command and control acti¬
vities through electronic warfare. Obviously, loss of communications la
likely to degrade performance in other areas, especially maneuvering.
However, most other writers appear to take a narrower view and consider
the degraded performance to be a direct result of behaviors resulting
from fear of incapacitation.

It should be noted that the contemporary definitions of suppression
attempt to deal with observables, l.e., behaviors, while the earlier
works relied on a purely mental concept of fear. It should also ba
noted that these behavioral definitions objectively permit anchoring the
ends of any suppression scale. If no decrement in performance can be
observed (regardless of what Individual members of a force may state
about the intensity of their fears), suppression is rated saro. If all
observable behavior is devoted solely to the minimizing of personal
risk, suppression is said to be complete or 100X. In other words, if
the fire intensity is such that an individual devotes his total effort
to aeeklng greater cover, he is totally suppressed. Increases in fire
power beyond this intensity cannot therefore increase suppression.
Despite these objectively defined end points, the measurement of the
degree of suppression along the scale has proven to be difficult and
controversial. For example, given a known level of fire, la it possible
to relate the degree of suppression of a force with extremely limited
mobility, but with the ability to observe the enemy and return fire, to
that of a force with the ability to observe and maneuver, but with e
limited capability of returning fire? Most likely, in either case the
ability to observe the enemy will be the last function suppressed.
However, the absolute or even the relative importance of each of these
functions is difficult to establish. Furthermore, the degree of sup¬
pression is also dependent upon the mission. If he is adequately pro¬
tected and concealed, a soldier observing enemy movement may be hardly
suppressed by enemy machinegun fire. Under the same conditions, the
soldier whose mission is to advance on the enemy might well be totally
suppressed.

It can be plausibly argued that at any given time, suppression is
either total or nonexistent. For example, assume that an infantrymen is
in a foxhole observing the enemy and firing as enemy personnel reveal
themselves. Movement at this time is not a pert of his mission.

Further assume that machinegun fire suddenly begins to rake the ares.

The soldier will undoubtedly duck into his foxhole end abandon attempts
to observe, return fire, or move. That is, he will be completely sup¬
pressed. However, shortly after the machinegun fire ceases, he will
again observe and fire on the enemy. In thiB sequence of events, the
soldier will go from being virtually unsuppreosed, to being totally
suppressed, to being virtually unsuppressed again. Although not ex¬
plicitly stated as such, this line of thinking probably led the CDEC
team^2 to view suppression as the percentage of time an individual was

Project Team II, op.

ait.

1-3

li li-i'k. 1 , jfc i**Li jrd'

unable to perform a specific assigned duty during a given period of
time. If one is willing to assume that suppression is always either
near 0 or near 100%, the "percent time suppressed" is a very reasonable
measure of the degree of suppression. As can be seen, attempts to
define, much leas measure, the degree of suppression have been fraught
with problems.

In all of the literature located, the authors agreed that suppres¬
sion was a "temporary" phenomenon. However, the meanings attached to
temporary were quite variable. Huggins, ^ reported on a CDEC Btudy in
which a target was said to be suppressed if two projectiles passed with¬
in two meters of the target within an .04 minute time interval. The
duration of suppression was .06 minutes, but could be extended for .01
minute for each projectile that passed within two meters of the target
while it was suppressed. Translating this into seconds, the minimum
suppression time appears to be 3.6 seconds, which is incremented by .6
seconds for each additional round. Kinney*^ states that "suppression is
a short-term transient degradation...," and defines "short-term" as
being "in the order of tens of seconds." The Ad Hoc Croup ^ points out
that most suppression models use constant durations with suppression
time tunning from 10 to 60 seconds. They question the use of these
short periods by noting that in the recent Mideast: War, a nen-kiliing
hit on the turret would cause a tank crew to stop activity for aB much
as 8 to 10 minutes. Unfortunately, actual combat data relating type and
intensity of fires, the range of individual behaviors, and the duration
of suppression are practically nonexistent. Therefore, the current
authors view these time estimates as merely "best guesses." Most attempts
to determine the duration of suppression have been based on retrospective
interviews of combat-experienced personnel. Variations in combat situ¬
ations such as the types and intensity of fires, thr> amount and kind of
protection, the relative size of the opposing forces, and the experience
and personalities of the individuals make it extremely difficult to
systematically compare the recollections of different individuals.
Furthermore, the validity of retrospective data is always suspect,
particularly when any behaviors reported could reflect adversely on the
Interviewee. Therefore, it is not surprising that the literature reports
great variability in the estimated duration of suppression.

To further complicate the issue. Investigators have stated that
suppression can be either "reasoned" or "unreasoned."^' Reasoned sup¬
pression is said to occur when an individual attempts to optimize the
tradeoffs between his personal protection and the accompl Islunent of the
mission. 'Unreasoned suppression is said to occur when the risk-reduc¬
tion behavior is far out of proportion to the actual threat. Unfortu¬
nately, what seemB reasoned to one may seem foolhardy to another, and

^Huggins, op. oil,

Kinney, op. oil.

US Department of the Army, op. oil.

Winter and Clovis, ,?;j. or l.

1-4

vice versa. As the Ad Hoc Group pointed out, "reasoned performance"
in a given situation must be defined. How does the individual weigh hie
personal survival against the importance of the mission? How does one
realistically assess personal risk? Can the reasonableness of perfor¬
mance at any given time be evaluated in terms of percent casualties
experienced? These and other similar questions must be answered before
criteria for reasonableness can be determined. At first, it might seaai
that an Individual who performed as if suppressed while not under fire
was exhibiting "unreasoned performance." However, this is not neces¬
sarily the case. Suppression csn bs divided Into two categories—
reactive and threat. Reactive suppression results from being taken
under fire. Threat suppression occurs when there is a high probability
of being taken under fire (especially if protection Is poor). Kinnay*®
refers to this letter kind of suppression as "anticipatory" suppression.
He states that anticipatory suppression is based on a future risk, while
reactive suppression is based on a current risk.

Naylor^0 implies that weapons designers need more information than
is supplied by definitions of suppression alone. The weapons designer
needs to know the particular characteristics of a weapons system which
are associated with specific behavioral responses. The earlier data
generally indicate the proportion of respondents who reported fear of
each of a particular set of weapons. Data on why the weapons were
feared tends to be sparse. Naylor presents data from an earlier study
indicating that such thingB as accuracy of fire, lack of warning,
rapidity of fire, noise, and a lack of defense ware typically stated aa
raasona for fsar of various weapons. Yet, inconsistencies existed. For
example, noise was a frequently cited reason for fear of diva bombers.
However, nolae did not appear to be a major factor in a fear of artil¬
lery shelling. Naylor's thesis is that wa know virtually nothing about
the separate or combined contributions of weapons characteristics In
terms of their effects on human behavior. In his point of view, ths
problem is:

...really one of assessing t{ie effect of a par¬
ticular stimulus, which is occurlng under a
particular set of circumstances or within a
particular environment, upon the behavior of an
individual or a group of individuals.

US Department of the Army, op. ext.

18 Ibid.

Kinney , op. oit.

J. C. Naylor, et al. Proceedings of the First Symposium on
the Psychological Effects of Non-Nuclear Weapons, Volume I , University
of Oklahoma Research Institute, Norman, April 29, 1964.

1-5

Stated somewhat differently, we will be able to effectively assess the
psychological effects of weapons, or, to predict the responses to new
weapons systems only when we are able to quantify both the stimuli
associated with weapons and the responses obtained from use of these
weapons.

At this Juncture, it might be well to examine why it is so impor¬
tant to predict the bahevlorel responses to the visual and auditory
signatures of weapons. One reason, as Naylor pointed out, Is that such
information might be useful in designing future weapons systems. How¬
ever, it ie also critical that ws know what responses should be expected
to employment of existing weapons systems. Many decisions concerning
the makeup and deployment of our armed forces are based on computer
simulations of hypothetical future engagements. The results obtained
are only as good as the input data and assumptions underlying the models
used. Obviously, if suppression does in fact exist, then it should be
played as part of the engagement. However, as was pointed out earlier
in this discussion, attempts to model suppression heretofore have been
baaed on "beet gueases" of the modelers. The variability in how sup¬
pression is handled in the different models indicates an urgent need for
better date. Inaccurate modeling of suppressive effects can only lead
to leas accurate decisions. Therefore, any data which improve the
modeling efforts should be extremely useful. This research was initi¬
ated as an attempt to relate stimulus characteristics of selected mall
come to psychologically scaled values of indexes of suppression and
perceived dengerouenees of each of these weapons. Hopefully, the re¬
sults can be employed to improve combat models, and, as Naylor has
suggested, provide useful information to weapons designers.

Chapter 2

RESEARCH PROBLEM AND LITERATURE REVIEW

Research Problem

Introduction. Kushnick and Duffy reported on a series of studies
slued at relsting the characteristics of small arms to their suppression
capability. In an effort to generate hypotheses, Hiey completed an ex¬
tensive review of the literature and conducted interviews with a large
number of combat veterans. They concluded that miss distance, caliber,
and rate of fire were the primary determinants of suppressive capabil¬
ity. Based on their analyses of the literature and Interview data, they
designed a series of experiments to verify their hypotheses. In one of
these studies, observers were placed In a pit and given a scenario de¬
scribing a hypothetical battle situation in which they were to Imagine
they were Involved. Small arms were then fired over the pit from a
range of 150 maters. Varying lateral miss distances were employed.

Miss distance was controlled by aiming the weapons at a series of tar¬
gets emplacdd on the opposite side of the pit from the weapons. After
each sequence, observers were asked to select one of seven alternative .
statements which would best describe their behavior under these circum¬
stances on an actual battlefield. These alternatives are shown In Table
2-1.

These alternatives were later scaled in terms of the amount of
suppression each represents through the use of Delphi techniques. These
scaled values are shown In the second column of Table 2-1.

Following this, each respondent's reply to each situation vas
assigned the appropriate scale value, and the values were averaged
across respondents and conditions to develop a suppression Index for
each weapon. The weapons and their scale Suppression Index (SI) values
are shown In Table 2-2.

In another experimental study, data on perceived dangerousness of
live fire events were obtained in the same physical environment de¬
scribed above. However, rather than a behavioral type scale such as was
used In developing the Suppression Index, dangerousnass was rated on a
simple 7-polnt scale. The anchor points were "no personal danger" and
"maximum dangerousness," Zt was concluded that the major factors
producing a perception of dangerousness are the loudness of passing

^S. A. Kushnick and J. 0. Duffy. The Identification of Objeotive
Relationehipa Between Small Avne Five Chavaoteviatioe and Effeotiveneee
of Suppve8eive Five, TR 72/002, Final Report, Mellonics Systems Develop¬
ment, Litton Industries, Sunnyvale, California, 3 April 1972. (For a
less technical version, see G. M. Glviden, "Weapons Effectiveness and
Suppressive Fire," in Pvoaeedinge , 13th Annual US Army Operations
Research Symposium AORS XIII, 29 Oct. - 1 Nov., 1974, Fort Lee, Virginia,
Vol II, pp 503-513.

2-1

Table 2-1. Response Alternatives to Fire Events

Baaponee Alternative

Delphi Scale

k . Take cover ae beet 1 could, but
wouldn't be able to obeerve or

fire on the enemy at all. 100

B. Take cover aa beat 1 could and
would be able to observe the
enemy occaaionally, but wouldn't
be able to fire at the enemy at

all. 90

C. Take cover aa beat 1 could and
would be able to obaerva the
enemy continuoualy but wouldn’t
be able to fire at the enemy at

all. 80

D. Take cover aa beat I could, and
would be able to observe the
enemy occasionally and fire at

the enemy occaaionally. 59

E. Take cover aa best I could, and
would be able to observe the
enemy continually and fire at

the enemy occasionally. 34

F. Take cover as beet I could, but
would be able to observe the
enemy continually and place

continuous fire on the enemy. 17

0. Would continue doing what I had
been doing before the incoming
fire and wouldn* t worry about

gattlng better cover. 0

Value

rounds, the proximity of putting rounds, and the volume of fires.

Since the proximity of passing rounds and the rates of fire w re held
constant, it was concluded t at the loudness of the passing roundB was
the primary determinant of differences in perceived dangerouanesa in the
experiment. Loudness was believed to he closely related to the kinatlc
energy of the projectiles as they paused near the subjects. Howavar,
the relationship between kinetic energy and perceived dangerouanesa
proved to be curvilinear. The tabled data, adapted from Kuahnlck and
Duffy, are shown in Table 2-3. From this result, it can be concluded
that either (a) kinetic energy is not linearly related to perceived
loudness, or (b) other factors in the acoustic signature are at play in
determining perceived dangerouanesa. It is interesting that the two
weapons which caused the curvi linearity are those with the highest
(XM645 flachstte) and lowest (.45 caliber) velocities. It is conceiv¬
able that the frequency spectrum and duration of the sounds from Chess
projectiles at the extremes of velocity may affect their perceived
dangerousness above and beyond the loudness component. However, Kuah¬
nlck and Duffy made no attempt to relate these characteristics to par-
calved dangerousness. In fact, no data on projectile signatures wera
obtained during the study. However, with interest in suppression still
high, it was felt that it would be useful to determine whether or not
other aspects of the auditory signatures of the projectiles could ba
employed to Improve the prediction of perceived dangerouanesa. There¬
fore, this effort was initiated to (a) determine what information on tha
auditory algnaturas was available or could be made available, and (b) to
determine whether these data could be employed to improve tha prediction
of tha paychologically-derived measures by physical measures.

Approach. As originally conceived, this effort was to be conducted
in two phases. The initial phase was to be an attempt to locate data on
tha auditory signatures of the small arms projectiles employed in the
Kushnlck end Duffy studies. However, it was also deemed advisable to
accomplish an update review of the literature to determine If any rele¬
vant work had been accomplished since the vary complete reviaw reported
by Kushnlck and Duffy. A portion of the material reviewed was smploynd
In the background discussion in Chapter 1. Additional discussion of the
literature will follow in the next major section of this chapter.

The second phase of the effort was to be an attempt to relate the
auditory signature data of the small arms projectiles to the psycho¬
logically-scaled values of suppression and perceived dangerousness. It
was determined that only available data on auditory signatures should be
used at this time. An attempt to obtain new data was viewed as too
costly. The instrumentation required for obtaining accurate data on

Another study was conducted to determine the suppressive effect of
the vieusl signatures of Impacting rounds. While these signatures were
related to suppression, they did not play a part in the experiments in
which the Suppression Index and the Perceived Dangerousness Index were
derived.

Table 2-2. Suppression Scale Scores

Weapon

Mean SI

Standard Deviation

XM19

29.82

23.41

M16

35.10

22.83

AK47

36.44

24.84

H60

43.27

23.72

Caliber .30 MG

60.99

30.77

Table 2-3. Relationship Between Kinetic Energy (KE)
and Perceived Dangerousness

Projectile

KE x 10“8

Perceived Danger
ouaneas Index

Caliber .50

27.79

M60

3.63

AK47

2.20

Ml 6

1.33

Caliber .43

.93

XM643

.94

2- A

auditory signatures is highly sophisticated (e.g., see Garlnthsr and
Moreland**), and simply not available. In addition, duplicating the
conditions under which Kushnick and Duff's subjects perceived the pass¬
ing rounds would also be difficult. Therefore, it was felt that the
available data should first be analyzed. If these data showed signifi¬
cant promise for predicting the psychological Beales, then a determina¬
tion would be made as to the desirability of obtaining new and more
complete data on the auditory signatures.

Unfortunately, all of the data desired could not be located.
Nevertheless, some further analysis of Kushnick and Duffy's data seasaed
warranted. The results of this analysis are presented in Chapter 3.

Discussion of the Literature

The primary source of the literature obtained was the Defanss Docu¬
mentation Center (DDC). However, personnel at the Human Knglnearlng
Laboratories (HEL) , Test and Evaluation Command (TECOM) , Plcatinny
Arsenal, the Army Environmental Hygiene Agency (ABHA), and the Ballistic
Research Laboratories (BRL) were also contacted in an effort to insure
complatenesa. The emphasis in the searches was on the more recent
literature; that is, literature published since the review by Kushnick
and Duffy. However, because of their perceived high relevance, a number
of documents referred to by Kushnick and Duffy were also obtained. An
attempt was also made to limit the documents obtained to those which
dealt with the suppression of infantry units, and/or suppression rs-
sultlng from the use of small arms. A considerable portion of the
effort was also invested in the search for auditory signature data of
small arms. The search in DDC was complicated by the Inconsistency in
the use of key words. For example, there were over AO entries for the
M16 rifle and associated equipment. While it was possible through
proper coding of entries to form some groups for the searches, the
process was still quite tedious. For example, by use of proper input
codes, it was possible to retrieve information on all documents having
key words such as M~16, M-16 rifle, M-16 rifles, M-16 gun, and M-16
guns. However, separate searches had to be made for documents with key
words such as M 16 and M16. Also, in order to retrieve documents
related to suppression, a variety of key words such as suppression, fire
suppression, and weapons systems effectiveness had to be employed. All
In all, approximately 100 combinations of key words were employed in the
DDC searches.

The general literature on suppression can be divided into three
broad categories. The older documents were primarily reports of inter¬
view and/or questionnaire studies. The newer documents dealt primarily

0. R. Garlnthsr and J. B. Moreland. Trmeduoer Teohniquee for
Measuring the Effect of Small -Arms Noioe on Hearing, Technical Memorandum
11-65, US Army Human Engineering Laboratory, Aberdeen Proving Ground,
Maryland, July 1965.

letifa f

with field experiments or the development of models for use in gaming .
However, few of the reports reviewed were "pure" in that they fell
exclusively into one of the three categories. Also, many of the reports
contained substantial theoretical or general discussions of the nature
of the phenomenon of suppression. Nevertheless, for convenience of
discussion, the literature reviewed will be divided into the three
categories suggested above.

Interview and questionnaire studies, some of the general findings
of the interview end questionnaire studies have already been presented
in Chapter 1, and will not be repeated here. The reader Interested In a

more detailed unclassified review and discussion of .these studies is
referred to Naylor, et al.,4' or Casey and Larimore." However, there are

a number of conjectures concerning interview and questionnaire studies
that are of sufficient Interest for at least a brief mention. For

example, Palmer, et al. point out that data obtained from POWs need to
be scrutinised very carefully before validity can bo assumed, as POWs
may deliberately attempt to mislead the interviewer. Palmer, et al.
also point out that many such studies employed structured Interviews
which may have tended to lead the interviewees. Questionnaires also
tend to be structured In nature. Palmer, et al, recommend the use of
an unstructured Interview sa the most valid approach.

There is evidence from the interview and questionnaire data that
familiarity with a weapon tends to reduce fear of that weapon. Or, in
the case of the especially effective weapons, fear may actually In¬
crease. In other words, familiarity with weapons tends to make fears
more realistic. That is, the relative fear of various weapons is likely
to become more in keeping with the actual casualty-producing ability or
lethality of the weapon, ae familiarity with the weapon Increases.
However, this wee not always found to be the case. In some cases,
greeter feer was expressed for those weapons which had most frequently
been used egelnet the individual being questioned. Fear was also found
to be associated with the reputation of a weapon. For example, US
forces In Africa during WWII expressed great fear of the German "88"
becauae of its reputation for extreme accuracy.

J. C. Naylor, et al. Proceedings of the First i'ynrpos ucn on the
Payahologioal Effects of Non-Nuclear Weapons - Volume 1 , University of
Oklahoma Research Institute, Norman, April 29, 1964.

^1. J. Casey end W. E. Lerimore. Para)>hyei,<al Variables in Weapon
System Analysis, AR 66-1, Analytic Services, Inc., Falls Church,
Virginia, April 1966.

^J. D. Palmar, et al. Investigation of Psychological Effects of
Non-Nuclear Weapons for Limited Wav. Volume No. II, Experimental
Studies, ATL-TR-65-39, Vol II, Directorate of Armament Development,
Weapons Division (ATWR) , ERlin AFB, Florida, January 1966.

2-6

Although the evidence Is nor substantial, there are some indica¬
tions that fear of weapons Is at least in part culturally deterained.
These data have been reviewed by Casey and Larlmore,'' They present data
from Kahn® comparing the fears of Chinese Communist forces and North
Koreans to United Nations weapons. A portion of these data is shown aa
Table 2-4. However, Kahn suggests that other than cultural differences
may account for the differences observed in the table. He suggests, for
example, that different types of weapons may have bean used against the
two forces, or that different proportions of combat-axparlenced soldiers
may have served in the two armies represented. Casey and Larljaore also
present data on fear responses to a first air raid. It was found that
Russians wars laaa frightened than either French or Italians. Further,
the Russians tended to fear large bombs the most out of fiva possibili¬
ties, while the French placed large bombE^ third. Both groups, along
with Italians, placed incendiary bombs last.

Table 2-4. Most Feared United Nations Weapon a

Percent

Weapon

Chinese North Korean

Airplane

Strafing

Bombing

Napalm

Artillery

Machlneguns

Tanks

Tank Guns

Rifles

No. of Prisoners

238

305

The lnconaietency of reports concerning the affect of noise has
already been mentioned in Chapter 1. That la, noise was vary frequently
mentioned as a reason for fear of dive bombers, while it waa virtually
never mentioned in connection with fear of artillery. Page, et el..

•7

Caaey and larimor?, ait.
g

L. A. Kahn. A Preliminary Investigation of Chinese and North
Korean Soldier Reactions to UN Weapons in the Korean War, ORO-T-14
(FEC) , Johns Hopkins University, 1952.

M. M. Page, et al. "Prior Art in the Psychological Effacta of
Weapons Systems," in J. C. Naylor, et al., Proceedings of the First
Symposium on the Psychological Effects of Non-Nuclear Weapons - Volums
I, University of Oklahoma Research Institute, Norman, April 29, 1964.

2-7

point out that the British had little fear of "shrieking" bombs. This
was because of the time they could be heard before they hit. Thus, they
had ample warning and could take cover, rendering the bombs largely
ineffective from the antipersonnel standpoint. This la in direct con¬
trast to the data on fear of the shrieking dive bomber cited earlier.
However, the troops reporting fear of the dive bomber were in the open
end therefore had little affordable protection. Hence, it can be seen
that situational factors are extremely important In determining what
characteristics of a weapon will produce fear.

Experimental studies, only two series of experimental studies were
located in the literature search. One of those was the series of five
studies reported by Kushnick and Duffy. 0 The general procedures em¬
ployed in most of this series has already been described in the Research
Problem section. The first experiment was a "policy capturing" experi¬
ment designed to determine what personal as well, as weapon and scenario
characteristics contributed to suppression ratings. It was during this
experiment that the Suppression Index was derived. The second experi¬
ment was a miss distance estimation experiment, and the third dealt with
the perceived dengerousness of various live fire events. The fourth
etudy was designed to assess the suppressive effects of impact sip, na¬
turae, and the fifth to determine whether physiological responses were
correlated with the psychological responses to live fire events. Data
collection for the impact signature study differed somewhat from the
other experiments. Rounds were actually fired into the ground approxi¬
mately 15 maters in front of the pit, and subjects observed the impacts
through periscopes. The general conclusions drawn from this series of
studies were: (1) the major factors producing suppression are the loud¬
ness of passing rounds, the proximity and number of passing rounds, and
th i signatures associated with roundB impact ing. (2) Within the limits
of *;ha study, suppression was shown to (a) decrease in a linear fashion
with increasing miss distance, (b) to increase linearly with increases
in rate of fire or volume of fire, and (c) to Increase in a linear
fashion with increases in the perceived loudness of passing projectiles.
This series of studies by Kushnick and Duffy will also be referred to
hereafter as the Litton studies.

The US Army Combat Developments Experimentation Command (USACDEC)
conducted a series of suppression experiments employing a wide variety
of both direct and indirect fire weapons. Data from two of the more
relevant experiments have been summarized in a 1976 publication. The
intent of these studies was to determine the proximity of fire required

■^Kushnick and Duffy, op, ait.

Deputy Chief of Staff for Combat Developments, US Army Combat
Developments Experimentation Command, Fort Ord, California. USACDEC
Suppraeaion Experimentation Data Anah/ttin It port, April 1976.

2-8

to suppress at the .5 and .9 probability levels, and to determine the
volume of fires required to obtain the warm.' suppression levels. The
suppreesees were ATCM gunners who simulated the engagement of a ma¬
neuvering armored element with an antitank missile. However, the
suppreesees did not have the capability of engaging the base of suppres¬
sive fires. The ATGM gunners used periscopes to detect, acquire, end
track the armored vehicles. In order to motivate the ATGM gunners,
rewards were given based on points obtained. The defenders were given
maximum points for fully exposing their periscopes in firing at the
enemy. Fewer points were awarded for partially exposing the periscopes
and observing without firing, and no points were awarded for keeping the
periscope down in the foxhole unable to fire or to observe. Negative
points were given if the periscope was hit by the suppressive fire. It
was assumed that each ATGM gunner would have to remain exposed for IS
seconds to complete the engagement. That is, If a gunner withdrew his
periscope during the course of the engagement, it was assumed that the
missile wee "lost" and that the engagement would have to be re-initi-
ated. Suppressive fire wbb placed at predetermined points in a pre*~
determined pattern and rate by a team of "attackers." The likelihood
that an ATGM gunner would be suppressed at each of several miss dis¬
tances was determined empirically for each weapon Involved. Weapons
employsd in the CDEC studies which were also employed in the Litton
study were the .50 caliber machinegun, the M60 machinegun, and the H16A1
rifle. It was discovered that the probability of suppression is Influ¬
enced by proximity of fire in a relatively orderly or predictable manner.
It wee possible to model radial miss distance in meters by the following
equation:

RMD - AeB

PCS)

Where: RMD is the miss distance In meterB

P(S) is the probability pf suppression

A and B are constants associated with each specific weapon
type.

For the M60 machinegun, A ■ 89.556 and B » 5.395. Figure 2-1 presents e
curve drawn through points computed for miss distances of .5, 1, 3, 6,
10, 15, and 20 meters. As can be seen, a miss distances of 6 meters
results in a .5 probability of suppression, while a miss distance of
lees then 1 meter is required for a .9 probability of suppression. It
should be noted that the data entering into each of the models wee based
on the results of all of the studies in which a particular weapon was
involved, if the data were considered valid.

Probability of Suppression

Figure 2-1, Probability of suppression as a function of radial tidsa distance

Another CDEC study Investigated the effect of concealment on aup-
pression. As might be expected, targets in concealed poaitiona ware
leaa suppressed than those in visible positions. However, an intareat¬
ing but unexpected result was obtained. There waB a consistent tendency
for the M16A1 in the semi-automatic mode to be more suppressive than in
the automatic mode. In other words, rounds fired singly over a 30-second
period tended to be more suppressive than rounds fired in 3-round bursts
when the same total number of rounds were fired per unit of time. The
authors speculate on this finding thusly:

Since automatic fire is often believed to be
more suppressive, the M16A1 on eeml-automatic
should have bsen the leaBt suppressive of the
dispersions used. The results indicate that
this may not be true; in fact, the aeoi-auto-
matlc condition tanded to be one of the moat
aupprasslve dispersions. Since 18 rounds per
event were fired in each of the seven disper¬
sions, there were six opportunities to suppress
targets in the three-round burst mode, and 18
such opportunities in the semi-automatic mode
during each 30 second trial. Therefore, the
greater volume of fire associated with each
trigger pull on the three-round burst may not
compensate for the increased number of trigger
pulls available with the same number of rounds
in the semi-automatic mode. When the targets
were visible, each trigger pull often was in
direct response to sighting a target; there¬
fore, the targets could be suppressed more
times during a trial by the semi-automatic
mode. The fact that the semi-automatic mode
received a more suppressive ranking for visible
than concealed targets supports this conjecture.

It seems to the present authors that an attempt should be made to repli¬
cate the finding just described. If the finding can be replicated, it
should prove useful to both commanders and to weapons designers. The
ability to fire rounds singly saves both ammunition and wear and tear on
weapons, and may be equally or more effective in suppressing a hostile
force.

One major difference between the CDEC studies and the Litton
studies was that CDEC relied largely on objective data, while Litton

Project Team II, US Army Combat Developments Experimentation
Command, and Braddock, Dunn, and McDonald Scientific Support Labora¬
tory, Fort Ord, California. Viepereion Against Concealed. Targete
(PACTS), USACDEC Expeinment FC 023, Final Report, July 1975.

2-11

2 ^

relied on subjective data. However, only one notable discrepancy in
the conclusions drawn has been detected. Data from the CDEC study were
suggestive of a logarithmic relationship between miss distance and level
of suppression (see Figure 2-1). The Litton study concluded that "with¬
in the limits of the study," suppression wbb found to decrease in a
linear fashion with increasing miss distance. However, the explanation
for this apparent difference may be found in differences in the experi¬
mental procedures employed. In the CDEC studies described, the rounds
mey have actually passed closer to the observers than in the Litton
study. Also, though it ia not stated in the reports, the observers may
have seen muzzle flashes and observed round impacts as they were em¬
ploying periscopes above ground level. In the Litton studies where the
Suppression Index and Perceived DangerouaneBB Index were derived, the
observers were below ground and had no opportunity to observe muzzle
flashes or impacts. Furthermore, the targetB at which the weapons were
fired ware above ground level. From the description presented In the
Litton report, the present authors estimate that the nearest miss dis¬
tance wee approximately 3.5 meters. Note that in Figure 2-1, that moat
of the curvilinearlty occurs below 3.5 meters. That is, the curve Is
relatively straight at ranges from 3.5 meters up. If only these data
were available, it would be easy to conclude that the relationship was
linear. Tha CDEC reports present no data relative to the Litton con¬
clusion that suppression increases with the perceived loudness of pass¬
ing projectiles. Both sets of studies conclude that the proximity and
number of passing rounds are associated with suppressive behavior.

Model S

General aonaideratione .

The belief that suppression does, in fact, exist, and does affect
the outcome of battles, has provided the impetus for the development of
mathematical models of suppression for inclusion in computer battle
simulations. To the extent that the models realistically portray sup¬
pression affects, the computer simulations are improved. However, the
authors of virtually all the documents describing model development
admit that the model's are based on assumptions and require validation.
Furthermore, the assumptions vary from model to model. For example, in
tha FAST-VAL model, ^ it is assumed that an attacking battalion will
break when they have 20% casualties and an attacking company will break
when they have 30% casualties. It is further assumed that a defending

CDEC also collected subjective data during the DACT5 study but
found it more variable than the objective data, and therefore, placed
greater reliance on the objective data.

S. G. Spring and S.. H. Miller. FAGT-VAl,: Ho.lat.vonohvpo Among
Casualties , Suppre onion, <md the Perfonnannn of t'nmpawj-Gi: te Lfriit.it,

RM-6268-PR, Rand Corporation, Santa Monica, California, March 1970.

2-12

battalion will break when they reach 40 % casualties and a defending
company will break when they reach 50% casualties. Johnson’6 points
out that the theater battle model assumes that an attacker breaks
contact when he suffers 15% casualties, while a defender breaks contact
after suffering 30% casualties. Obviously, both sets of these assump¬
tions cannot be correct. Also, the use of a fixed percentage doss not
seen to bs realistic. An Operations Research Office report**9 describes
the snslysls of a number of battles in which US forces were both in
attack and defensive postures. The breakpoints proved to be quite
variable from battle to battle. All of the conditions leading to this
variation could not be ascertained. However, such factors at the total
length of the battle and the availability of reinforcements appear to be
factors. The authors also suggest that the quality of leadership and
expsrlenct of ths personnel may have been factora. The influence of
factors such ss these must be determined before the models can be re¬
fined.

As discussed in Chapter 1, there ia also disagreement on the dura¬
tion of suppression. The Ad Hoc Group^ noted that most models assume
constant durations of 10 to 60 seconds. Again, the employment of a
constant value seems unrealistic. Concealment, for example, was shown
by CDECJS to be related to suppression time, with concealed targets
being leas suppressed than targets in the open. Other fectore ere
undoubtedly Involved. However, refinement of this espect of the models
must wait the eccumulation of data delineating the contribution of the
various factors. Further experimental research, end possibly further
analysis of past battles, are required.

Work conducted by the Systems Research Center at the University of
Oklahoma suggests tha difficulties that are likely to be encountered In
attempts to refine battle simulations to fully account for psychological

E. C. Johnson, Jr. "The Effect of Suppression on the Casualty
Exchange Ratio," Masters Thesis, Navel Postgraduate School, Monterey,
California, March 1973.

D. K. Clark. Casualties as a Measure of the Loss of Combat
Effectiveness of an Infantry Battalion, TM-ORO-T-289, Operations
Research Office, Johns Hopkins University, August 1954.

US Department of the Army, Office of the Deputy Chief of Staff
for Research, Development, and Acquisition, Washington, D.C. Report
of the Amy Scientific Advisory Panel Ad Hoc Group on Fire Suppression,
ODCSRDA Form 11, 7 July 1975.

1 8

Project Team II, op. cit.

2-13

1 ')

variables. For example, Terry, et al., ' formulated a psychological
index of weapons effectiveness. They described the psychological index
as "a system of measurements. vh:.i. will permit quantitative description
of the psychological effects o' v gone." The index is referred to as
the SRC Psychological Index, where S stands for signature value, R for
reputation value, and C for context value. The signature variables are
sound spectrum, sound intens tty, 1 ight spectrum, light intensity, injury
capability, and flame capability. Despite the multiplicity of factors
considered, Terry, et al., did not mention impact signatures, which the
Litton studies showed did affect psychological ratings. The reputation
variables are familiarity, experience, predictability, forewarning,
accuracy, lethality, countermeasures, and protection. Under context ere
listed 16 force variables, 10 unity variables, and 4 leadership vari¬
ables. Force refers to those factors relevant to the degree of military
might which can be employed by an enemy. Unity variables are those
which are relevant to the cohesiveness of an enemy unit, and Include
such things as propaganda effects, the reputation of the unit, and their
personal motives. The leadership variables pertain to leadership quality.
As can be seen, assuming that all of the variables listed by Terry and
co-workers are relevant to the psychological effects of a weapon, pre¬
diction of the effects is exceedingly complex. Terry, et al., were not
dealing specifically with suppression, but with psychological effects in
general. However, it is certainly conceivable that all of the variables
mentioned might be factors in the suppressive capability of a weapons
system.

Page, et al., delve into the responses to weapons systems. They
state that weapons-specif ic variables (e.g., weapon efficiency, visual
aspects, noise, duration, etc.) and situational variables (available
protection, proximity, leadership, mobility, etc.) form the stimulus
corplex which Impinges on the individual human, These variables inter¬
act with personal characteristics, which they refer to as organismic
variables. Organismic variables are defined as experience, expecta¬
tions, personal involvement, physiological condition, and predisposition.
The result is a set of responses. These responses are divided by Page,
et al., into immediate behavioral changes and long-range behavioral
changes. Immediate changes include such things as panic, immobility,
fatigue, poor performance, and flight or escape behavior. Long-range
changes might be lowered morale, irrational thinking, regression, or
even neurotic and psychotic disorders. This concept by Page, et al., of
course, assumes a behavioral response which is desirable from the stand¬
point of the weapon user. Otherwise, the weapon would have no relevant
psychological effect.

^R. A. Terry, et al. Development of Weapons Design Criteria Based
on the SBC Payaho logioa l Index: An Investigation of Signature , Depu¬
tation and Context E f feats t Technical Report AFATL-TR-8 7-185, Air Force
Armament Laboratory, Air Force Systems Command, Eglin AFB, Florida,
October 1967.

^Page, et al , , <>p. -‘it.

I',

i . •

The work of Page, et al., and Terry, pt al., does illustrate the
complexity of the problem of predicting the psychological effects of
weapons. However, It should be noted that the problem posed for this
present research is less complex. Kushnick and Duffy noted that their
respondents were reacting primarily to the sounds of the passing pro¬
jectiles. What Terry, et al. refer to as context variables probably
played an insignificant role. The situation or scenario given to each
respondent was only briefly described* and the responses were limited to
the seven choices presented. Organiamic variablaa undoubtedly did coma
into play. That la, each individual reacted in hia own individual
manner. No attempt, however, wae made to measure theee variables other
than to obtain a very limited amount of biographical information. There¬
fore, our present concern is almost solely with the aignature variablaa.

Huggins ■* presents an explanation of how the suppression phaonome-
non works.. Once a fire fight is Initiated, all combatants tend to taka
cover. The next reaction is to assume a firing position and attempt to
locate targets on which to deliver aimed fire. If no targets can be
detected, a normal reaction is to deliver area fire at the assumed tar¬
get location. Thualy, the fire fight tends to restrict the movement of
tha individual combatants. If one aide ia able to Increase its firs,
the other side is forced to take greater cover, is less able to detect
targets, and therefore, it less able to return fire. In this manner,
one side tends to assume fire superiority and the other side la said to
be suppressed. The more one side is suppressed, the less they can
deliver fire, and therefore the degree of suppression increases as tha
opposing aide is able to deliver even greater voluaea of fire. In
theory at laaat, one aide could become totally aupprasaad, allowing the
other aide to maneuver freely against them. However, In practice, there
la a limit to the amount of fire any one aide csn dsllvsr. Wsapon wssr
and ammunition supplies dictate some restraint. Also, unless soma of
the fires are lethal, the suppression will only result in a delay end
not s victory. In other words, the purpose of suppression appears to be
that of gaining the advantage in mobility and the ability to observe,
but mtytyt be followed by lethal fire in order to achieve e victory.

Tepee"" also discusses the purpose of suppression. He feels that it is
s harassment designed to fatigue the enemy by Interference with work-
rest cycle and biorhythms. Ideally, tha harassment weapons should

A. L. Huggins, Jr. "A Simplified Model for the Suppressive Effects
of Small Arms Fire," Misters Thesis, Naval Postgraduate School, Monterey,
California, September 1971.

D. I. Tepas. "Some Relationships Between Behavioral and Physio¬
logical Measures During a 48-Hour Period of Harassment; A Laboratory
Approach to Psychological Warfare Hardware Development Problems, " in
J. C. Naylor, et al., Proceedings of the First Symposium oyi the Fsy -
ohologioal Effects of Non-Nuolear Weapons - Volume I, University of
Oklahoma Research Institute, Norman, April 29, 1964.

fatigue the enemy to the extent that he eventually falls into a deep
sleep, and is therefore completely suppressed. That this may actually
happen is attested to by an incident reported by Page, et al.2^ They

state;

An example of hyperreaction is given in a report
from a company pinned down while on the offensive
in Korea. While undergoing intense fire and in¬
fighting for several, hours, officers reported at
mid-day that their most difficult problem was
keeping the men awake and firing their weapons.

This feeling of fatigue and extreme sleepiness,
where it was not physically justified, was an
avoidance hyperreaction to an especially in¬
tense weapons effect.

Tiedemann and Young*'^ present an interesting notion on suppression
which Is essentially weapons-independent. They suggest that successive
impacts of rounds coming closer and closer to an individual are likely
to be more suppressive than rounds going in the other direction, or
rounds randomly placed, or all hitting in the same spot. Whether this
is true or not, it has a logical appeal. It might even be assumed that
Impacts at successively greater distances from an individual would
hardly have any suppression effects at all.

Burt, et al., report on an interesting finding which certainly
seems to be related to suppression. In an analysis of several battles,
it was found that as artillery strength increased, the relative propor¬
tion of casualties by artillery decreased. The same apparently contra¬
dictory relationship was also found for small arms. This may be ex-
pi lined in part by assuming that Increases in one kind of fire power
caused personnel to take cover from that kind of fire power. However,
it is difficult to Imagine that personnel taking cover from artillery
fire would not also be protected from small arms fire. Nevertheless,
Burt, et al., suggest this possibility. They state;

It seemB reasonable to expect that when the enemy
artillery fire power is great, stronger friendly
bunkers are constructed and unnecessary friendly
movement ia curtailed. Tn addition, Increased

f) a

‘' Page, et al.,

24 . .

A. F. Tiedemann, Jr. and R. B. Young. Index of Promxtty: A

Technique for Scoring Suppressive Fire, ER 6419, AAI Corporation, Balti¬
more Maryland, October 1970.

^ j , A. Burt, et al. Distribution of Combat Casualties by Caueative
Agents, Technical Memorandum RAC-T-445, Research Analysis Corporation,
McLean, Virginia, March 1965.

2-16

enemy artillery fire power may have been employed
to allow the enemy infantry to come into direct
contact with the friendly forces where they would
make use of their amall-arms weapons. This would
reduce the percentage of casualties caused by
artillery but increase the percentage caused
by enemy small arms.

The authors also point out that their data are based on the relative or
proportionate number of casualties. That is, lncraaaaa in artillery
fire power may also cause increases in the absolute number of casual¬
ties, but msy still comprise a relatively smaller proportion of the
total casualties.

In closing this genera^ discussion section, reference la mads to
the work Winter and Clovis, who followed up on the earlier work by
Kushnick and Duffy. These authors were unable to find any quanti¬
tative data on suppressive effects. Due to this lack, they analysed
over 100 anecdotal reports of combat situations from WWII, Koras, and
Vietnam. The level of suppression was determined Judgmtntally by com¬
paring the behaviors described in the various reports. Unfortunately,
quantitative data on a number of crucial variables such aa volumes of
fire were not available. Therefore, considerable subjectivity was in¬
volved in the analysis. They searched specifically for data on sig¬
natures, including visual, auditory, olfactory, seismic, and thermal
signatures. They divided signatures into platform signatures, initi¬
ation algnaturas, trajectory signatures, and terminal algnaturas.
Supprasslvs sffscts were noted on the ability to firs, move, observe,
and cossaunicata . The authors concluded that the "expected fraction of
casualties," or lethality expectations associated with the weapon, takes
into account all of the multiplicity of characteristics considered by
others. Therefore, the model they developed had one parameter for
weapons performance and one for "subjective aspects associated with
human beings. This conclusion, that lethality is the only weapon
parameter Involved In suppression, certainly has appeal. If true,
weapon signatures as such play no part in suppression except as recog¬
nition aids. That is, if the signature Identifies the weapon as being
of high lethality, it will lead to greater suppressive behavior.

However, the present authors feel that this approach is too simplistic,
aa lethality la only one of a number of relevant factors. Other studies
have consistently shown that fear of a weapon and its casualty-producing
ability are not perfectly related, even among highly experienced battle
veterans, But, until the contribution of other factors, if any, can be
determined, the use of a single factor such as lathallty msy be the bast
approach. With regards to the human factors Involved, these authors

R. P. Winter and E. R. Clovis. Relationship of Supporting Weap¬
on Systems Perfomanoe Characteristics to Suppreeeion of Individuate
and Small Unite, TR 73/002, Defense Sciences Laboratories, Mellonics
Systems Development Division, Litton Systems, Inc., Sunnyvale, Cali¬
fornia, January 1973.

2-17

make an Interesting recommendation. They recommend that no further
experimentation on suppression be done. They feel that the suppression
phenomenon is too complex and that the state-of-the-art in the behav¬
ioral sciences is not sufficiently advanced to yield any results of

practical value.

Invariant models.

No attempt was made to locate information on all of the computer
battle simulations devised by the military services. Many of the models
originally examined did not play suppression at all, and will not be
discussed here, There are undoubtedly others which do play suppression
on which no information was located during the literature search. A
complete reporting and description of the models reviewed did not seem
necessary, as they had much in common. Therefore, the models which will
be briefly discussed below should be considered as only a sampling of
the total universe.

The models developed to date are largely Invariant. That is, there
is no "human factor" built into the assumptions. A given fire event in
a given circumstance always results in the same degree and duration of
suppression. This does not mean that the authors do not realize that a
human factor exists. Most admit that it does, but that they lack the
means for quantifying it. So, in essence, the models assume an "aver¬
age" behavioral response on the part of the suppressed force. However,
as discussed earlier, there is a notable lack of agreement on such
things as the duration of suppression and the breakpoints (in terms of
percent casualties) at which a force will abandon its mission.

A brief review of some of the major features or characteristics of
lome of these models is presented below.

a. Kushnick and Duffy used kinetic energy of the projectiles as a
first approximation of the suppressive effects of a weapon. (See pages
2-1 through 2-3 of this chapter.) As mentioned earlier, they found that
a curvilinear relationship existed between kinetic energy and perceived
dangerousness. This particular finding will be discussed more fully in
Chapter 3. The authors do acknowledge that factors such #8 the nature
of the mission, availability of cover, combat experience, training, time
in combat, and basic psychological makeup of the individual do mediate
the suppressive effects of weapons. However, they make no attempt to
deal with these variables in studying the relationship between kinetic
energy and individual variations in perceived danger ousnesB . They
present data dealing with only the average of the responses.

b. Aiken, et al., employing the data obtained by Kushnick and
Duffy, attempted to 9cale weapons effects between 0 and 10OX suppres-

A. C. Aiken, W. L. Phillips, and I>. V. Strlroling. "Individual
Suppression as Induced by Direct Fire Solid Projectile Weapons: Itu
Effect and Duration," (U) , ART paper, '(0 April 197b.

H Ion . To do thin, tlioy viMHumed LluiL no flruu would roBuJt in no nup-
presuion, and Chat a specific level and proximity of fireB from a given
weapon would result in 100% suppression. Employing Che kinetic energy
of projectiles, they were able to derive constants for their equations
which relate all fires to this scale. However, they were quick to point
out that once suppression reached 100%, that no additional fires could
result in a greater degree of suppression. In other words, once the
critical level of fires was achieved and suppression was complete.
Increasing fires would have no further suppressive effect and would
therefore be wasteful.

c. Kinney, though concerned with the development of a model for
predicting suppression effects from fragmenting explosive warheads,
assumes that miss distance is the only criterion for determining sup¬
pressive behavior. However, since various miss distances for various
weapons represent different kill probabilities, he assumes that is
actually the physical variable which induces the psychological response
of suppression.

d. Like Kinney, Tiedemann and Young^ assume that the proximity of
Impacting rounds is the determinant of suppressive behavior, and they
develop an index based on impact distances. Moreover, they state that
successively closer impacts result in greater suppression than Impacts
at successively greater distances. However, they make no attempt to
deal with individual differences or the effects of specific signatures
of weapons systems.

e. Burt, et al. attempted to relate such things as enemy per¬
sonnel strength, artillery fire power, small arms fire power, ammunition
supply, and weather to the Incidence of casualties caused by either
artillery, small arms, bombs, etc. Other qualitative variables were
considered, such as terrain, vegetation, and morale, but were discarded
because data were simply not reliable or were Incomplete, Ammunition
supply was discarded because data were not available In many instances.
Burt and his co-workers analyzed data for five WWII battles and 16
Korean battles. They obtained a multiple correlation of .85 for pre¬
dicting casualties from artillery, and a correlation of .77 for predict¬
ing casualties from small arms. However, conflicting results were
obtained in the validation attempt. The equations failed to predict
casualties in another battle from WWII, but were quite good in predict¬
ing casualtlee from another battle in the Korean War. In devaloplng the
equations, small arms were considered as a single category and casual¬
ties produced by different kinds of small arms were ell considered to be
the same. While the correlations are quite substantial, they do fall to

Kinney, op. ait,

;>! 3

Tiedemann and Young, op, att.

account for a considerable portion of the variance. In other wordB,
measures of weapons lethality alone are not necessarily good predictors
of casualties. The observed differences in casualty rates between
battles may have been due to differences in enemy firing accuracy (i.e. ,
proximity of impacting rounds). It may also have been due to differ¬
ences in the protection available for or experience levels of the
friendly forces. Both of these latter factors would also be ejected to
be related to suppressive behavior. If these factors were also at play,
measures of lethality (including proximity measures) alone would be
expected to predict neither caaualties nor the degree of suppression of
friendly forces. Further data are needed to determine the contribution
of the various factors.

The models described indicate something of the range and types of
models which have bean developed. There are many others. The Ad Hoc
Group, for example, presents a table listing the major characteristics
of six other models of varying sophistication, all of which appear to be
of the invariant type.

models .

The models which include a human factor also make many of the .same
kinds of assumptions as the invariant models. That 1b, the weapons
effects portion of the models is typically calculated in the same manner
as in the invariant models. However, the final results are modified by
introducing a human factor.

a. pie SRC Psychological Index developed at the University of
Oklahoma5^ represents an attempt to model all of the non-weapons spe¬
cific factors in weapons effects. Strictly speaking, the Index is not a
midel since a means for numerical computation of index values was not
provided. Rather, it simply provides a framework for a model which 1b
in need of validation. Since this psychological index was discussed at
some length earlier, no further details will be presented here.

b. Winter and Clovis'^ developed a model based on the expected
fraction of casualties and a human factors coefficient. The expected
fraction of casualties was based on the number of rounds fired, the
lethal area per round, the area over which target elements are dis¬
persed, and the circular probuble error. They state that the human
factors coefficient (rho);

...represents the aggregate of effects of human
factors and other Intangibles relating to
morale, leadership, tactical situation, fear/
danger ratio, and so forth; it has a nominal

•^Terry, op. ait.

Winter and Clovis, op. a-it:.

2-20

value of 1. Use of values greater than 1
Implies conditions resulting in higher sup¬
pressive levels than the threat would typically
elicit; Inexperienced troops, for example. If
conditions are such that lower than typical
suppression levels will occur, as might be in
the case of a crucial defense by veteran troops,
then a value of rho less than 1 is appropriate.

Unfortunately, the value of the human factors coefficient must be deter¬
mined subjectively.

c. FAST-VAL II (Forward Air-Strike Evaluation)^ is a model de¬
veloped by the Air Force "...to define in analytic terms those relation¬
ships that describe the performance of a wall-led and well-disciplined
infantry company during a fire fight." Weapons effects are modeled in
FAST-VAL by computing casualties baaed on the numbers of personnel in a
given area and the levels of fire directed against them. The vulnera¬
bility of personnel is determined by the posture of the personnel. For
example, personnel may ba assumed to be in the prone position, stendlng
in foxholes, crouching in foxholes, or in log bunkers. When the cas¬
ualty rate exceeds a given value, personnel revert to a lass vulnerable
posture. Less vulnerable postures represent suppressed states. When
the casualty rata for a given period of time is less than some fixed
number, personnel revert to a more vulnerable posture. The human factor
la built into the model by the user in two ways. One, the user deter¬
mines the casualty rate at which a force will seek their second, more
suppressed posture. Two, the user selects a fractional efficiency for
each of the postures available in the model. In this way the user
determines both whan suppression will occur and what its effect will be
on the performance of the suppressed individuals. At least according to
the description provided by Spring and Miller,34 percent casualties is
the only factor entering into suppression, This seems a bit unrealistic
in terms of what other investigators have found about behavior under
fire.

Although they made no attempt to model the human factor, other
writers have indicated that human factors variables ought to be included
in models. For example, Reddoch, though presenting a wdel of the
Invariant type, suggests that human considerations may e. ter the re¬
lationship between lethality and suppressed behavior, he suggests that
when a weapon becomes too lethal, it nay have no suppressive effect at
all. Reddoch Invokes tl.-j concept of "negative suppression" for this

Spring and Miller, op. ait.
Ibid.

R. Reddoch. "Lanchester Combat Models With Suppressive Fire and/or
Unit Disintegration," Masters Thesis, Naval Postgraduate School, Monterey,
California, March 1973.

2-21

contingency. If a weapon Is so lethal that the target individuals be¬
lieve that seeking protection will be useless, then they will make an
all-out effort to destroy the weapon before It hits them. He cites
flamethrower tanks as such weapons during WWII. Normally, personnel in
bunkers would be suppressed by fire from conventional tank weapons.
However, the flamethrowers represented a threat of near-certain destruc¬
tion regardless of the bunker, so that virtually any risk appeared
Justified to destroy the tanks. The same situation held when gun boats
In Vietnam had their 40mm weapons replaced by the 105mm howitzer. The
40mm's were replaced because they had proven ineffective against enemy
bunkdrs. The 105mm was able to penetrate and destroy the bunkers. The
result, of the change was Increased friendly casualties, Again, the
enemy felt that since the bunkers offered virtually no protection, they
were not suppressed, continued to fire, and inflicted heavier casualties
on friendly forces.

Casey and Larlmore concluded that both the culture In which person¬
nel ware raised and their Individual personalities affected their
reactions to various kinds of weapons. They suggested the concept of a
"modal personality" to account for these kinds of differences. Casey
and Larlmore also feel that the situation la an important determinant of
behavior under fire. The situation is made up of the physical objects
and conditions (cover, mobility, etc.). However, the authors suggest
that It la more the combatant's perception of the situation than the
actual situation which Influences his behavior.

To recapitulate, virtually all of the model makers, even those who
developed Invariant models, believe that a human factor exists. How¬
ever, attempts to Include human variation in models have been rudi¬
mentary at best. It Is obvious Chat a great deal more work needs to be
doi.a to define the situational, cultural, and Individual variables which
influence behavior under fire.

Casey and Larimore, on.

l fit.

2-22

Chapter 3
ANALYSIS

The original intent of this effort was to determine whether any
aspect of the acoustic signatures of the weapons employed by Kushnick
and Duffy^ could aid in predicting the Suppression Index and Perceived
Dangerousness Index they derived. Based on their own observations, plus
reports from their subjects, they felt that the acoustic signatures of
the passing projectiles were virtually the sole determinants of the
ratings made. They stated:

It was the opinion of both the subjects And
the DSL analysts that the basic stimulus that
allowed the subjects to perceive and note the
dangerousness of the events in the field ex¬
periment was produced by the projectile signa¬
tures and not by the characteristics of the
muzzle blasts of the weapons themselves....

* The obvious overt characteristic producing
the perception of dAnger is the loudness of
the signature of passing projectiles....

The purpose of the present exercise was to obtain some notion on what
aspect or aspects of the signatures affected suppression other than
perceived loudness. Such information, if later proven valid, might be
of considerable use to both conmandars in the field and to weapons
designers. It was, of course, realized that any results would be ten¬
tative, due to the small number of weapons involved in the study.
However, the results were not intended to provide the ultimate solution.
Rather, they were only Intended to suggest hypotheses to provide direc¬
tion to further experimental work on suppression.

Unfortunately, the data desired could not be located. Much of the
relevant data located were not in the open literature, but rather were
obtained from the files of various agencies through personal contacts
with individuals in those agencies. All of the individuals contacted
expressed serious doubts that the type of data requested existed at all.
Two reasons were giver. First, the measurement of weapons signatures
was made almost entirely in the interests of safety. The efforts ware
directed towards determining whether weapon noises met design specifi¬
cations and/or exceeded the standards set forth in MXL-STD 1474 (MI),

a. A. Kushnick and J. 0. Duffy. The Identification of Objective
Relationships Between Small Arms Five Characteristics and Effectiveness
of Suppressive Fire , TR 72/002, Final Report, Mellonlce Systems Develop¬
ment, Litton Industries, Sunnyvale, California, 3 April 1972.

Department of Defense. "Noise Limits for Army Materiel," MIL STD-
1474 (MI), Washington, D.C., March 1973.

3-1

i -SV L/S-- V. ;

... .

"Therefore, measurements were typically taken at the tiler's ear, and at
distances up to two meters to the left and right of the muzzle. These
latter measurements were to determine whether or not the weapon posed a
hearing hazard to adjacent individuals. In the case of weapons fired
from a vehicle, measurements were taken at the various crew positions.

It was pointed out, that at least with smull arms, there was little
concern about the safety of individuals 150 meters down range, as
friendly troops were unlikely to be in such positions. Only two studies
were located where down range measurements were obtained. Second, the
instrumentation required to accurately measure weapons signatures is
extremely sophisticated and is believed to be available only to research
and development agencies. Therefore, personal contacts felt that If any
such data were available, it would have been obtained by or known to
personnel at the various agencies contacted. Since none of the personal
contacts recalled having seen any such data, they felt that it was
unlikely to have ever been obtained.

The data which were obtained dealt largely with peak sound pressure
levels and with the durations of the A and B waves. Some analyses of
the sound spectra were available, but were judged to be of little use.
First of all, most of the measurements were made near the weapon and
contained blast as well as projectile noiaeB. Secondly, there appeared
to be no clear-cut differences in the spectra that were easily quanti¬
fiable. For example, Garinther and Kryter^ provide data showing that
the M16 spectrum has a relatively flat amplitude between 0 and 15,000
hertz, except for short bandwidth dips around 7000 and 9000 hertz. The
spectral analysis of the Ml 4 is similar, except that the big dip in
amplitude centers at about 12,000 hertz with a smaller one at 3000
hertz. Several other weapons showed no such missing bands in the lower
p irt of the audible spectrum. With the small number of weapons for
wl ich suppression indices were available, attempts to use these types of
data did not appear warranted.

Although most of the measurements of acoustic signatures were
obtained near the weapon to evaluate hearing hazards, some data were
obtained down range. These data were not obtained to evaluate the
suppressive qualities of the weapons. Rather, they were obtained to
determine the. ranges at which passing projectiles could be detected and
to ascertain whether the actual location of the weapon Itself could be
determined. These data, reported by Garinther and Moreland,^ indicate

^ ...

*G. R. Garinther and K. D. Kryter. Auditory and Aeous ti oal Evalu¬
ation of Several Shout dor RijS-cn, Technical Memorandum 1-65, US Army
Ihunan Engineering Laboratories, Aberdeen Proving Ground, Maryland,

January 1965.

^ G, R. Garinther and J. R. Moreland. Aeons 1 foal Considerations
for a Silent Weapon System: A Feasibility Study, US Army Human Engineer¬
ing Laboratories, Aberdeen Proving Ground, Maryland, October 1966.

3-2

the complexity of the problem addressed by this effort by enumerating
the wide variety of factors which affect dovm range acoustic signatures
of projectiles.

Meteorological conditions, especially humidity and wind (both
direction and velocity), were found to have significant effects on
audibility. Similarly, the density of vegetation was found to influence
the signature. The mental state of the listener wsb also found to be
Important. For example, subjects whose sole task was to await and
attend to projectile nolaes detected at greater ranges than subjects who
were also attending to another task. However, division of attention
should not have been a factor in the Kushnlck and Duffy study. All
subjects were told to attend solely to the weapon signatures. Varia¬
tions In meteorological conditions might have had an effect, but these
data were not reported by Kuahnick and Duffy. Photographs of the test
site show that vegetation in the area was negligible. Therefore, vari¬
ations in vegetation from subject to subject or time to time could not
have been a factor. However, had there been vegetation, the acoustic
signatures might well have been quite different. Garinther and Moreland
alao present data comparing the spectrum obtained at 80 meters with that
obtained 2 meters from a weapon. It Is obvious from the graphs present¬
ed that considerable wave form distortion occurred during the propagation
over an open field. Exactly how the spectrum is Influenced with in¬
creasing range Is not specified. However, Garinther and Moreland do
indicate that the differences are noticeable to the human ear.

Only one study was located which measured peak sound pressure
levels down range. Garinther and Mastagllo5 placed microphones down
range at 115 yards, 315 yards, and 515 yardB. Rounds were fired 10 feet
over the microphones. They found that both peak sound pressure levels
and durations were essentially constant from 115 yards through 515
yards, That is, peak SPLs varied by less than one decibel (dB). The
peak for the M14 rifle was approximately 20 dB less than that measured
near the muzzle. However, measurements at the muzzle, averaging 167.5
dB, were obtained from four feet from the left and right of the muzzle.
The down range measurements, ranging from 147.1 to 147.8 dB, were ob¬
tained from the greater distance of 10 feet. A comparable decrement of
20 dB was also obtained for the AR 15, a .223 caliber weapon. Since the
down range measurements were taken at a greater distance from the flight
path, a lesser SPL would be expected. Unfortunately, Garinther and
Mastagllo made no measurements 10 feet from the muzzle itself. Never¬
theless, the loss in peak SPL down range appears not to be great.

However, the duration of the impulse was shorter down range. For ex¬
ample, measurements of the duration four feet from the muzzle of the M14
varied from 3.0 to 3.4 milliseconds. The down range measurements varied
from 1.0 to 1.1 milliseconds.

1 G . R. Garinther and G. W. Mastagllo. Measurement of Peak Sound-
/’rcHBure Levels Developed by AH lb and Ml 4 Rifle Bullets in Flight, US
Army Human Engineering Laboratories, Aberdeen Proving Ground, Maryland,
January 1963.

3-3

Oerinther and Moreland present some other data which appear to be
highly relevant. In their effort to determine Lho characteristics ol
projectiles which minimize acoustic signatures, they found that, projec¬
tiles which tend to yaw produce louder noises. One type of projectile
they tested could be heard from only two or three meters at short ranges
away from the muzzle. However, yaw began to increase down range from
the muzzle, end at 150 meters down range it could bo detected at much
greater distances from the flight path. The authors attributed this to
the shape of the projectile. Therefore, any tendency to yaw may he
expected to alter the signature of a projectile rather markedly an It
proceeds down range.

From the preceding discussion, it can be seen that a whole host of
factors affect the down range signatures of passing projectiles. In
other words, one must know what the meteorological conditions are, what
type of terrain is being fired over, and what type (shape) of projec¬
tiles ere fired before the acoustic signatures at any point down range
can be known. Many of these factors were not reported by Kushnick and
Duffy. However, even if they were, the data required to predict the
exact signatures at 150 meters are simply not available. Therefore, it
is impossible to know at the present time exactly what was heard by
Kushnick and Duffy's subjects, Had their subjects been slightly closer
or slightly farther away, or had meteorological conditions been diffe¬
rent, the suppression indices obtained might have bean different. As a
result, it can only be assumed that the indices obtained are represen¬
tative, and would remain relatively stable across a variety of ranges
and meteorological conditions.

Despite the reservations implied in the previous discussion, and
the general paucity of data on weapons signatures, the data reported by
Kush lick and Duffy are worthy of further consideration, first of all,
the question of the reliability of the indices should be examined. It
can be noted in Table 2-2 that the variability of the ratings for each
of the weapons was quite large in comparison to »he mean. Generally,
this indicates that the distributions were skewed, but it also indicates
that there were wide differences In Individual oxpecLat Ions of behaviors
under fire. However, the means may still be quite stable, an each mean
is based on a large number of observations.

Based on Kushnick and Duffy's work, both Winter and Clovis/ and
Aiken, et al.,7 employ kinetic energy as the nearest physical correlate

R. P, Winter and E. R, Clovis. idn'al.iou
Systems Performative CharavLc vis ties to Supprai

Small Unite , TR 73/002, Defense Sciences Labor
terns Development Division, Litton Systems, Inc
January 1973.

. "J Suppor: ; iiy tv'i.’i ipo>i
't/i. of !>: { iv: duals and

itories, Hellenics Sys-
. , Sunnyvale, California,

A. C. Aiken, W. L. Phillips, and I). V. Stringing. "Individual
Suppression as Induced by Direct Fire Solid Projectile Weapons; Its
Effect and Duration," (U) , ART paper, 30 April 1975.

3-4

of subjective loudness In attempts to develop models of suppression. It
is Interesting to note that Garinther and Moreland were also concerned
with subjective loudness. They considered peak SPL, energy, impulse,
and phons (ASA procedure) as correlates of loudness for subsonic pro¬
jectiles. They concluded that impulse was the best measure, and that
impulse was proportional to the cross-sectional area of the projectile.
For supersonic projectiles they state:

The primary factor which determines a supersonic
projectile's loudness is the shock strength it
generates. In turn, the strength of the shock
wave depends primarily on the projectile's
maximum diameter.

However, they do not provide a means for computing the subjective loud¬
ness of a subsonic projectile to place its value on the same seals aa a
supersonic projectile. Both Winter and Clovis, and Aiken, et al., as¬
sumed that Kinetic Energy (KE) was the correlate of loudness rather than
diameter. Diameter is not necessarily proportional to KE ae both total
mass and velocity are involved. Nevertheless, it should be noted that
the M60 projectile, with a KE x 10“8 0f 3.63 received a perceived
dangerousness rating of 41 (see Table 3-1). The AK 47 projectile, while
having a KE x lO”® of only 2,20, received a perceived dangerousness
rstlng of 39. Both projectiles have a diameter of 7.62mm. The close¬
ness of the psychological values provides some support to the notion
that diameter is a primary factor in subjective loudness.

Table 3-1.

Relationship Between Projectile Diameter, KE, and
Perceived Dangerousness

Weapon

Projectile

Diameter

KE x 10"8

Perceived

Dangerousnaas

Caliber .50

12. 7mm

27.79

M60

7 . 62ram

3.63

AK 47

7.62mm

2.20

M16

5. 56mm

1.33

Garinther and Moreland do not state that diameter and subjective
loudness are linearly related. Certainly, a linear relationship between
diameter and perceived dangerousness was not established by Kushnlck and
Duffy's work, A graph portraying the relationship between weapon and
perceived dangerousness is presented in Figure 3-1. It la obvious that
the .45 caliber weapon, which had the second largest diameter of those
Involved, was perceived as being among the least dangerous of the six
weapons studied. The .45 cnllber weapon was, of course, the only sub¬
sonic projectile among the six. Therefore, as can be seen from Figure

Figure 3-1. Perceived dangerousness as a function of kinetic energy

3-1, its position among the other weapons would not be a function of its
diameter.

Although the signature data desired were not available, some fur¬
ther examination and analysis of the data presented by Kushnick and
Duffy seemed warranted In light of other works. As was noted in Chapter
2, there were some apparent discrepancies between the conclusions drawn
by the CDEC investigators® and the Litton investigators.^ For example,
the CDEC team found a logarithmic relationship between miss distance and
suppressive behavior. The Litton team concluded, that within the limi¬
tations of their study, the relationship was linear. As pointed out in
the previous discussion, this quite possibly could have been due to
differences in the actual miss distances employed. However, a nonlinear
relationship might have been postulated on a priori grounds. It is well
known that the physical energy of an auditory stimulus decreases with
the square of the distance from the receptor, Hence, on a priori
grounds, one might expect a second degree equation to provide the best
fit to miss distance data (see Figure 2-1, Chapter 2, page 2-10); Of
course, exponential equations and second degree equations can take very
similar forms. In either case, most of the curvllinearity tends to
occur near the origin, or in this case, it would be expected to occur at
the lesser miss distances, In the Litton studies, it is estimated that
the observers were a minimum of approximately 3.5 maters from the
pesslng rounds. This would place the minimum miss distance from the
observer's ears on the more linear portion of the curve.

In the Litton studies, Kushnick and Duffy show a graph portraying
the relationship between kinetic energy and the psychological variable
of perceived dangerousness. This graph was shown earlier as Figure 3-1.
The curvllinearity of the relationship is obvious from the graph.
Kushnick and Duffy reported no attempt to fit a curve to the observed
data. The shape of the curve, however, might have been expected, again
on a priori groundB. It has been known since the days of Weber aud
Fechner that the relationship between physical and psychological scales
tended to be exponential in nature. If kinetic energy is Indeed di¬
rectly proportional to the physical energy of the auditory stimulus,
then an exponential relationship between kinetic energy and perceived
loudness could be postulated. In any event, an attempt to fit an ex¬
ponential curve to the data appeared to be worthwhile. Kushnick and
Duffy do not report the perceived dangerousness ratings, so the values

Project Team II, US Army Combat Developments Experimentation Com¬
mand, and Braddock, Dunn, and McDonald Scientific Support Laboratory,
Fort Ord, California. Dispersion Against Conoealed Targets ( DACTS )t
USACDEC Experiment FC 023 , Final Report, July 1975.

Kushnick and Duffy, op. ait.

3-7

employed were read from the graph. The equation derived for predicting
perceived dangeroutmess from KE x 10~8 is:

PD - In [ (x-a)/b1
c

where x ■ KE x 10"®

a - .927182
b - 4.28471 x 10"7
c - .382161

A computed perceived dangerouaness value was obtained for each of the
alx weapona employing the above equation. Table 3-2 lists the weapons,
the kinetic energy of the projectiles as computed at 150 meters as com¬
puted by Kuehnick and Duffy, the perceived dangerousness ratings read
from Kuahnlck and Duffy's graph, and computed perceived dangerousness
ratings obtained from the equation.

Tsbls 3-2.

Computed and Actual Perceived Dangerousness
Ratings Based on Kinetic Energy

Weapon

KE x 10“8

Actual PD

Computed PD

Csllbar .50

28.00*

47.00

M60

3.63

40.97

AK 47

2.20

39.00

M16

1.33

35.99

C* liber .45

.93

23.01

XM 645

.94

26.97

*For ease in computation, 28.00 was substituted for the actual
value of 27.97.

A correlation of r * ,96 wau obtained between the actual and the com¬
puted ratings. While a correlation of thia magnitude is impressive, it
must be remembered that the relationship was based on only six data
points. Nevertheless, the psychological scale are means based on a
large number of observations, and so should be relatively stable.
Therefore, the result provides a reasonable indication that the per¬
ceived dangerousness of passing rounds, in the exact situation employed
bv Kushnick and Duffy, may be quite accurately predicted from a knowl¬
edge of the weight and velocity of the rounds.

Extrapolation of the curve obtained provides some Interesting
results. For example, the equation Indicates that perceived dangerous-
n/'s approach’s 0 as KE x 10"® approaches .927182. In other words, a

projectile with a KE only very slightly less than the caliber ,45 would
be predicted to have virtually no value in suppression. Similarly, a
20tm weapon would be predicted to have a perceived dangerousness rating
of 49, only very slightly better than the caliber .50. Therefore, the
results indicate that It would probably not be logiatlcally efficient to
employ any larger weapons in suppression. However, it must be remem¬
bered that the predictions made would probably be applicable only in the
exact situation employed in the Litton study. Furthermore, it is very
possible that the actual shape of the curve is ogival. That is, at some
point below a KE x 10”® value of .93, the curve may turn toward the
origin so that a KE of 0 would result in a 0 rating of perceived dan-
gerousness. Since no data are available on projectiles with lesser KE
than the caliber .45, the actual shape of the curve below this KE Is
indeterminate.

A similar attempt was made to fit a curve empirically to the date
for the Suppression Index, The data on kinetic energy are the same as
shown in Table 3-2 and the SI ratings were taken from Table 2-2. The
equation derived is shown below.

SI - I" L(x-a)/b]
c

where x « KE x 10“8

a - .244383
b - .019885
c - .118728

The correlation between the observed and computed values of SI is r »
.99. Again, the fit is excellent. Employing this equation, it would be
predicted that a weapon with a KE x 10“8 of .264268 or less would not be
suppressive at all. Similarly, a 20mm weapon would be predicted to have
an SI value of 69. A weapon which would totally suppress return fires
(see Response C, Table 2-1, page 2-2) would have to have an SI of 80,
and a KE x 10“8 of over 260. The use of such a weapon for suppression
hardly seems practical, and the weapon would hardly be considered a
small arm. . Therefore, again, it seems that the caliber .50 weapon is
probably the largest caliber weapon that should be employed in a purely
suppressive capacity.

Although the mathematical models fitting the observed values of the
psychological scales and kinetic energy were excellent, it oust be
remembered that only six data point? were involved, and three of these
were employed in the empirical process of curve fitting. Nevertheless,
the fit to the remaining points cannot be ignored, Only the M16 rifle
fails to fall almost perfectly on the curves, and the deviation in
either case is probably of no practical significance. Therefore, it has
to be concluded that any further research into this area should first
look f.t KE as a variable in predicting psychological raaponses to weap¬
on!. If the results hold, it should not be necessary to look furthar at

3-9

signature values of passing projectiles. KE may well take into account
all critical aspects of the signature, ut least for existing small arms.
Of course, muzzle flash, muzzle blast, and Impact signatures were not
involved in the derivation of the equations, but, in circumstances where
they are evident, will undoubtedly play a role in determining behavior.

The worth, valued against the cost, of doing further research in
this area is a decision that must be reached by Army authorities.
However, if further research is deemed to be warranted, .t is recom¬
mended that the first step be an attempt to validate th~ usefulness of
KE as the sole variable in predicting responses to passing projectiles.
It is further recommended that a study of the relationship between KE
and lethality be made, to assess the validity of the models which employ
Pfc (taking miss distance into account) as the primary determinant of
suppression. Naturally, if possible, this effort should also consider
blast, flash, and impact signatures singly and in combination with KE.
All in all, such a program would be quite extensive in scope. As
mentioned 'earlier, the desirability of such a program will have to be
weighed against the desirability of other programs competing for limited
funds. Nevsrthelsss, the direction such a program should take, at least
at first, seems clear.

1-10

Chapter 4

RECAPITULATION AND RECOMMENDATIONS

A primary purpose of this research was to determine, from informa¬
tion available, what aspects of the acoustic signatures of projectiles
contribute to their being perceived as dangerous and/or result in sup¬
pressed behaviors. It was felt that no new data should be obtained at
this time unless it could be shown that variation in the acoustic sig¬
natures of the various projectiles was Indeed related to perceived
dangerousness or suppressed behavior as reported by participants. Very
little data on down range acoustic signatures could be found. However,
such data would probably have not been useful in any case. Factors such
as wind velocity and direction, temperature, humidity, vegetation, and
distance from the muscle have all been shown to affect at least some
aspects of down range signatures. Therefore, unless all these condi¬
tions were knowne, data on acoustic signatures would probably not be of
much value.

In further analysis of some previously reported data, kinetic
energy, which is believed to be closely related to the perceived loud¬
ness of passing projectiles, appeared to account for nearly 100Z of the
variance between weapons in both a Suppression Index and a perceived
dangerousness rating. Since kinetic energy at any given range from the
muzzle can be computed relatively accurately from firing tables, this
finding, if replicated, should prove useful in developing computer
models Involving suppression play. In the past, analysts have had to
rely on intuition and/or fragmentary and possibly unreliable descrip¬
tions of battles and behavior under fire.

Although the use of kinetic energy appears to hold great promise
for modeling suppression play, further research needs to be done. First
of all, the general stability of equations derived needs to be deter¬
mined. tn other words, the results of the re-analysis reported in
Chapter 3 need to be replicated. Moreover, additional work needs to be
undertaken. The indices derived in the Litton studies were based on
averages of ratings of several fire events. No means of partitioning
the data to determine the effects of either miss distance or rate of
fire on the scale scores is available. Additional work is needed to
develop equations for various kinds of projectiles at various distances
down range for each of several levels of miss distance and rate of fire.
In addition, data on sound spectra, peak SPLs, and durations of the A
and B waves should also bo obtained. In the event that kinetic energy
does not prove to be a reliable predictor of any scales employed such as
the Suppression Index or the Perceived Dangerousness Index, an attempt
could be made to relate these data to the scales derived.

REFERENCES

Aiken, A. C., Phillips, W. L. , and Strimling, D. V. "Individual Suppres¬
sion as Induced by Direct Fire Solid Projectile Weapons: Its Effects and
Duration," (U), ARI paper, 30 April 1975.

Burt, J. A., et al. Distribution of Combat Casualties by Causative Agente ,
Technical Memorandum RAC-T-445, Research Analysis Corporation, McLean,
Virginia, March 1965.

Casey, I. J. and Larlnore, W. E. Paraphyeioal Variables in Weapon System
Analysis , AR 66-1, Analytic Services, Inc., Falls Church, Virginia, April
1966.

Clark, D. k. Casualties as a Measure of the Loss of Combat Effeotiveneee
of an Infantry Battalion , TM-ORO-T-2B9, Operations Research Office, Johns
Hopkins University, August 1954.

Department of Defense. "Noise Limits for Army Materiel," MIL STD-1474
(MI), Washington, D.C., March 1973.

Deputy Chief of Staff for Combat Developments, US Army Combat Developments
Experimentation Command, Fort Ord, California. USACDEC Suppression
Experimentation Data Analysis Report, April 1976.

Dollard, J. Fear in Battle, The Institute of Human Relations, Yale
University Press, New Haven, Connecticut: 1943.

Garlnther, G. R. and Kryter, K. D. Auditory and Aoouatioal Evaluation
of Several Shoulder Rifles, Technical Memorandum 1-65, US Army Human
Engineering Laboratories, Aberdeen Proving Ground, Maryland, January
1965.

Garlnther, G. R. and Mastagllo, G. W. Measurement of Peak Sound-Pres¬
sure Levels Developed by AR15 and M14 Rifle Bullets in Flight, US Army
Human Engineering Laboratories, Aberdeen Proving Ground, Maryland,

January 1963.

Garlnther, G. R. and Moreland, J. B. Aoouatioal Considerations for a
Silent Weapon System: A Feasibility Study, US Army Human Engineering
Laboratories, Aberdeen Proving Ground, Maryland, October 1966.

Garlnther, G. R. and Moreland, J. B. Transducer Techniques for Measuring
the Effect of Small-Arme Noise on Hearing, Technical Memorandum 11-65,

US Army Human Engineering Laboratories, July 1965.

Givlden, G. M. "Weapons Effectiveness and Suppressive Firs," in Pro¬
ceedings, 13th Annual US Army Operations Research Symposium AORS XIII,

29 Oct. - 1 Nove., 1974, Fort Lee, Virginia, Vol II, pp 503-513.

Goldhamer, H. , George, A. L. , and Schnitaer, E. W. Studies of Pri aorta r-
of-War Opiniono on Weapons Effectiveness ( Korea ) (ll) , RM-733, Rand
Corporation, Santa Monica, California, December 1951.

Huggins, A. L. , Jr. "A Simplified Model for the Suppressive Effects of
Small Ansa Fire," Masters Thesis, Naval Postgraduate School, Monterey,
California, September 1971.

Johnson, E. C., Jr. "The Effect of Suppression on the Casualty Exchange
Ratio," Masters Thesis, Naval Postgraduate School, Monterey, California,
March 1973.

Kahn, L. A. A Preliminary Investigation of Chinese and North Korean
Soldier Reactions to UN Weapons in the Korean War, 0R0-T-14 (FEC) ,

Johns Hopkins University, 1932.

Kahn, L. A. A Study of Ineffective Soldier Performance Under Fire in
Korea , ORO-T-62 (AFFE) , Johns Hopkins University, 1954.

Kinney, D. C. Suppression Analysis Techniques (U), unclassified ver¬
sion of paper presented to 33 MORS, Weapons Planning Group, Naval
Weapons Center, China Lake, California, undated.

Kushnlck, S. A. and Duffy, J. 0. The Identi fioation of Objective
Relationships Between Small Arms Fire Characteristics and Effective¬
ness of Suppressive Fire , TR 72/002, Final Report, Mellonics Systems
Development, Litton Industriea, Sunnyvale, California, 3 April 1972.

Naylor, J. C.f at al. Proceedings of the First Symposium on the Psy¬
chological Effects of Non-Nuolsar Weapons , Volume I, University of
Okla >oma Research Institute, Norman, April 29, 1964.

Paga, M. M, , at al. "Prior Art in the Psychological Effects of Weap¬
ons Systems," in J. C. Naylor, at al.. Proceedings of the First
Sympoeium on the Psychological Effects of Non-Nuclear Weapons - Volume
I, University of Oklahoma Research Institute, Norman, April 29, 1964.

Palmer, J. D. , at al. Investigation of Psychological Effects of Non-
Nuolear Weapons for Limited War. Volume No, II, Experimental Studies,
ATL-TR-65-39, Vol II, Diractorate of Armament Development, Weapons
Division (ATWR), Eglin AFB, Florida, January 1966.

Project Team II, US Army Combat Developments Experimentation Command,
and Braddock, Dunn, and McDonald Sclsntlfic Support Laboratory, Fort
Ord, California. Dispersion Against Concealed Targets (PACTS), USACPEC
Experiment FC 023, Final Report, July 1975.

Reddoch, R. "Lanchester Combat Models With Suppressive Fire and/or Unit
Disintegration," Masters ThestB, Naval Postgraduate School, Monterey,
California, March 1973.

R~2

■ -*^7^ «• I r ^ o'7® *» n* -

,r p i“' r* -T7 ’VV^v , f " w^i /'TT’T' V.V * - ' 'r*1

Spring, R. G. and Miller, S. H. FAST-VAL: Relationships Among Casual¬
ties, Suppression, and the Performance of Company-Size Units , RM-6268-
PR, Rand Corporation, Santa Monica, California, March 1970.

Stouffer, S. A., et al. The American Soldier: Combat and Its After-
math, l foil II, Princeton, New Jersey: Princeton University Press, 1949,

Tepas, D. I. "Some Relationships Between Behavioral and Physiological
Measures During a 48-Hour Period of Harassment; A Laboratory Approach to
Psychological Warfare Hardware Development Problems," in J, C. Naylor,
et al. , Proceedings of the First Symposium on the Psyohologioal Effects
of Non-Nuclear Weapons - Volume I, University of Oklahoma Research
Institute, Norman, April 29, 1964.

Terry, R. A. Toward a Psyohologioal Index of Weapons effectiveness.

Part I. Field Studies , Technical Report 1419-5, University of Okla¬
homa Research Institute, Norman, December 1964.

Terry, R. A., et al. Development of Weapons Design Criteria Based on
the SRC Psyohologioal Index: An Investigation of Signature, Reputation ,
and Context Effects , Technical Report AFATL-TR-87-185, Air Force Arma¬
ment Laboratory, Air Force Systems Command, Eglin AFB, Florida, October
1967.

Tiedemann, Jr. and Young, R. B. Index of Proximity: A Technique for
Scoring Suppressive Fire , ER 6419, AAI Corporation, Baltimore, Maryland,
October 1970.

US Department of the ArAy, Office of the Deputy Chief of Staff for
Research, Development, and Acquisition, Washington, D.C. Report of the
Army Scientific Advisory Panel Ad Hoo Group on Fire Suppression , ODCSRDA
Form 11, 7 July 1975.

Winter, R, P, and Clovis, E. R. Relationship of Supporting Weapon Sys¬
tems Performance Characteristics to Suppression of Individuals and Small
Units, TR 73/002, Defense Sciences Laboratories, Mellonica Syatema
Development Division, Litton Systems, Inc., Sunnyvale, California,
January 1973,

APPENDIX B

Executive Summary of SUPEX IIIB Final Report (USACDEC)

F0RSW33D

1. AUTHORITY . Authority for the Suppression Experiment II IB (SUPEX
1 1 IB) was TRAOCC approved on 21 June 1978.

2. CORRELATION. The SUPEX II IB experiment is Identified as CDEC Experi¬
ment FC 02SG. Data from this experiment will be used to determine sup¬
pressive effects of static surface detonations on players when subjected
to an open foxhole condition. These effects will be compared to the
suppressive effects of static surface detonations on players when subjec¬
ted to a closed foxhole condition. The results will be used to determine
the feasibility of examining the suppressive effects of airbursts in
future experimentation. Related studies previously conducted include':

SUPEX; Suppression Experiment, United States Army Combat Developments
Experimentation Command, USACDEC, Fort Ord, CA, Feb 77.

3. CONTRACTUAL SUPPORT. Scientific Support Laboratory (SSL), USACDEC:
BDM Scientific Support Laboratory (Department of the Army Contract Num¬
ber DAAG-03-75-C-0105) .

4. ACKNOWLEDGEMENTS. Field participation in support of the experiment
was provided by the following agencies.

a. Player support from C Company, 2/31st infantry Battalion, 7th
Infantry Division, Fort Ord, CA.

b. Meteorological support from the Atmospheric Sciences Laboratory
Meteorological Team, U.S. Army Electronics Research and Development Com¬
mand, Fort Hunter Liggett, CA.

executive suaasflAav

1.1 PURPOSE. The purpose of Suppression Experiment II IB (SUPEX II IS)
was to generate data and measure the reasoned suppression produced by
statically detonated surface bursts of 60 mm mortar, 81 mm mortar, 105 mm
howitzer, and 155 mm howitzer rouncs. In addition, insights into physical
suppression caused by obscuration were to be obtained.

1.2 EXPERIMENT DESCRIPTION.

a. Experiment Objectives. There were three experiment objectives.

The first was to obtain data to determine the probability of suppressing
(P(s)j an Antitank Guided Missile (ATGM) gunner with single rounds of the
above mentioned ordinance as a function of detonation distance and aspect
angle from the gunner. The second objective was to gain Insights into
the probability of suppressing an ATGM gunner with volley fires from 105
on and 155 mm howitzers (surface burst). The final objective was to gain
insights into the effect of obscuration on the probability of suppressing
an ATGM gunner with the various type detonations. This objective was
added to the test after the project analysis was published.

b. Player Actions. The player's mission was to maximize the

number of target vehicle kills (HITS) while minimizing the number of times
he was assessed as a casualty. Four players were placed in seperate, open
foxholes in the center of the detonation area. Each player was to detect,
-s' t^ack, and simulate engagement of a moving target vehicle with an antitank

guided missile while simulated Indirect fire rounds were statically deto¬
nated on the ground surface at various ranges and aspect angles from the
player. After each detonation the player had to assess the hazard and
assume one of the three postures. (Fully exposed, partially exposed,
suppressed). If he remained in the fully exposed posture he could con¬
tinue to track and engage the target but had the highest probability of
becoming a casualty. If he remained partially exposed he could observe
tha’target but could not engage it, and he had less probability of becoming
a casualty. If he went to the suppressed posture he would not be assessed
as a casualty, but could not observe, track or engage the target. Two
seconds after the single round, and one n-’tor.d after the volley fire
detonations, casualties were randomly assessed. The assessment probability
of becoming a casualty was obtained from the Joint Munitions Effectiveness
Manual. The probability of becoming a casualty included the variables:

(1) "Player's posture.

(2) Range.

(3) Aspect angle to the detonation, and

(4) Size of the detonation.

(

The player's reactions to the detonations were automatically recorded
and time coded by the Data Acquisition and Recording System (DARS) and by
Closed Circuit Television (CCTV). The data were then analyzed to determine
the effects of the detonations on the players ability to perform the
assigned mission.

1.3 MAJOR FINDINGS.

a. Single Round Detonations. For any given range and round size,
the most suppressive detonations observed were directly In front of the
player (0 degrees). The observed least suppressive detonation varied
for each round size but was always behind the player. (The least sup¬
pressive aspect angle for 60 rrm, 81 rrm, 105 mm, and 155 irm was 180, 150, 180,
and 210 degrees, respectively.) According to player reports, this varia¬
tion In suppression was due to the lack of visual Information available

to them from detonations occurlng behind them. The players indicated they
used this visual Information in conjunction with aural Information to decide
whether to assume a suppressed posture, and if the visual cue was not
available, they were Inclined to remain in the least suppressed posture.

The fitted curves for the most and least suppressive angles of detonations
are presented In Figures 1 through 4 for each round size. For example,
the curves In Figure 1 indicate that If a 60 mm mortar shell was detonated
50 meters from a player, the probability of his being suppressed by the
detonation would be .47 if the shell exploded in front of him (0 degrees)
and .11 If It exploded behind him (180 degrees). Since artillery and mortar (.

w detonations occurred on aifferent trials, It Is inappropriate to compare
the data presentation In the figures for mortar detonations with those for
artillery detonations. The values of these curves corresponding to the
ranges used In the experiment are also presented In each of the figures.

b. Volley Round Detonations. The most suppressive detonations dur¬
ing the volley ^re were located to the player's front (0 degrees) and
the least suppressive detonations were generally at 90 or 180 degrees.

Again, the players reported that this differential suppressive effect was
due to the relative lack of visual information provided by detonations
outside their field-of-view. The observed data for the most and least
suppressive angles for each round size are presented in Tables 1 and 2.

Table 1, for example, displays an observed probability of suppression of
.88 at an angle of 0 degrees (directly to the player's front) for a

105 mm vollay detonated at a range of 85 meters. Because of the Investi¬
gative nature of volley fire, these data were not fitted to exponential
curves. In comparing the suppressive effects of single round and volley
fire the following results appear. At similar ranges the volley fires
appear to be more suppressive than single rounds. For 105 mm volley fires
the observed probabilities of suppression went from 1.0 at 45m to .35 at
125 meters. Over similar ranges the single round probabilities of suppression
varied from .55 to .08. Similar results were observed with the 155 mm
detonations.

(

c. Obscuration. For single round detonations, when obscuration

of the target vehicle was reported, the angle between the target vehicle
and the detonation (measured from the players' vantage point was generally
between >45 degrees. Some players stressed that during periods of
obscuration, they modified their tracking strategies depending on the
density end dispersion of the obscuring cloud. If the cloud covered too
wide an angle of view and/or remained for a considerable period, the
player went Into a suppressed posture. According to player questionnaire
responses, target obscuration was second only to the detonations themselves
as an important determinant of suppression. The players stated they
adopted a fully suppressed posture to avoid being assessed as a casualty
when the obscuring dust/smoke cloud prevented them from tracking the
target vehicle.

d. Training Benefits. Human Factors questionnaire results and
individual interviews showed that the players regarded the experiment as
very realistic training, particularly during the volley trials. The
experiment provided 7th Infantry Division player and support personnel
with realistic sights and sounds of the "dirty battlefield." This
realistic training experience enhanced player motivation throughout the
experl ment.

',.'•17 *; v** t rv.'.-.t; vat irnyw*.

PREDICTED PROBABILITY OF SUPPRESSION FOR 81 HR
AT 0 AND ISO DEGREES - SINGLE

PREDICTED PROBABILITY OF SUPPRESSION FOR 155MH
AT 0 AND 210 OEGREES - SIN6LE.

TABU 1 PROBABILITY OF SUPPRESSION AT THE MOST
SUPPRESSIVE ANGLES OBSERVED FOR EACH
RANGE FOR THE lO&r.n - VOLLEY

Range (maters

Most Suppressive
Angie

Least Suppressive

Probabi^1lJ>^,'^ Probability**-’''*'
Angle ^*-"*"*^ Angle Angle

0.88^^^^ | °.33

Li7mn

080)"

'TO

90A1B0)"

TABU 2 PROBABILITY OF SUPPRESSION AT THE MOST
SUPPRESSIVE ANGUS OBSERVED FOR EACH
RANGE FOR THE 155 m - VOLLEY

Probability

Range (meters

105

Probability

145

Probability

Angle

^0000^ Anal e 1

^*00*^ Anal e

LOO^

0^8^

— (o

1J.86

0.20

Angle

<4,*

DEPARTMENT OF THE ARMY

MCAOOUAMTEAS UNITED f TATtk AAMV TAAlNlNQ ANO OOCTAINE COMMAND
f CAT MONAOt, VIAQINIA 33401

SUPEX II IB Final Report

0 2 FEB 1979

SEE DISTRIBUTION

1. The SUPEX I I IB study has bean reviewed by Headquarters TRADOC.

2. The SUPEX IIIB experiment Is a significant step forward In reallstl
cally quantifying the effects of Indirect fire suppression.

3. Because of what appears to be contradictory results between mortar
and artillery trials, caution should be exercised If these data are con
sldered for use In models and simulations.

4. Future experimentation programs envision follow-on experiments to
produce more consistent mortar and artillery data.

FOR THE COMMANDER:

Assistant Adjutant General

ANNEX E - HUMAN FACTORS

Purpose; Scope ; Player Motivation: . E-]

Perceived Trial Realism: . .4 E-3

Projected Combat Risk; Determinants of

Suppression: . . . £-5

Suppression Cues: ................ B-20

Suppression Judgement Confidence: ....... E~13

Sumnary: . B-20

References: . . . E-21

Appendix 1 - Post-Trial Debriefing Questionnaires
Appendix 2 - Post- Experiment Questionnaires
Appendix 3 - Demographic Data

General; Volunteer Seleotion: ......... £-3~I

The Phenomena of Volunteering: ......... £-3-5

Searing Conservation; References: ....... £-3-3

ANNEX F - DATA PACKAGE

Purpose; General; Validation; Data Formats;

Data Cards: . . P-1

Appendix 1 - Data Card Formats

Appendix 2 - Meteorological Data

Appendix 3 - Human Factors Data Card Formats

\NNEX G - GLOSSARY

‘ #

ANNEX F - DISTRIBUTION

CONTENTS

(

PAGE

FOREWORD . 1

EXECUTIVE SUMMARY . 1

SECTION 1 - GENERAL

Purposes Obfeotivess Time and Place
of Executions Concept: ..... . 1-1

SECTION 2 - RESULTS

Generals Limitations! Measures of

Suppression: . . . . . 2-1

EEA 1: ..... . . 2-2

SEA 2: . 2-7

Obsouration: . . . 2-13

Player Performance: . 2-22

ANNEX A - EXPERIMENT DESIGN

Purposes Generals Design Considerations: .... A- 2
Appendix 1 - Schedule of Trial

Purposes Scope: . A-l-1

Appendix 2 - Round Detonatlon/Emplacsnent Schedules

Purposes Scope: ..... . A- 2-1

ANNEX B - INSTRUMENTATION

Purposes Generals System Description: . B-l

Quality Control: . . . B-?

ANNEX C - DATA ANALYSIS

„ Purposes Generals Least Squares Pit: . C-l

> Spearman's Rank Correlation Coefficient: .... C-2

■s

)

■■■i

■\

♦

PAfiE

Appendix 1 - Probability of Suppression for
Single and Volley Rounds

Purpose; General; Tabular Presentations
of MOE 2; Graphical Presentation of

HOE 1: ... \ . C-l-1

Alternative Measurements of Suppression: .... C-l-2

Appendix 2 - Quratlon of Suppression

Purpose; General ; Tabular Presentation of
MOE 2; Graphical Presentation of MOE 2: ... C-2-1

Appendix 3 - The Percentage of Players in Each

Intended Posture at the Time of Casualty
Assessment for Single Rounds

Purpose; General; Graphiaal Presentation: . , . C-3-2

Appendix 4 - The Most Suppressed Posture Assumed
by the Player Ouring Volley Fire

Purpose; General; Tabular and Graphiaal

Presentations: ......... . . . C-4-1

Appendix 5 - Obscuration of the Target Vehicle

w Purpose ; General; Graphiaal Presentation: . . , C-S-2

ANNEX D - OPERATIONS

Purpose ; Scope; General; List of Appendixes: . . D-l

Appendix ,1 - Range Operations

Purpose; Responsibilities: . D-l- 2

Appendix 2 - Site Selection and Design Layout

Purpose; General; Domrange Area: . 1 0-2-2

Target Vehicle Route: . D-2-2

Experimanigxtion Control Center: . D-2-5

APPENDIX C

Indirect Fire Suppression Model.
By

Phillip M. Allen (AMSAA)

(

TITLE: Indirect Ei re Put ; r.-rs lull Me Id
AUTHOR : Mr. Philip M. Allen

ACTIVITY: US Army Materiel Systems Analysis Activity, Aberdeen
Proving Ground, Maryland

I. INTRODUCTION

A. Special Projects Branch of the Ground Warfare Divieion, US

Army Materiel Pyr terns Analysis Activity, is presently developing Jointly
with the Royal Anrnnent Per-earch and Development Establishment (RARDE)
of the United Kingdom a simulation of combat at battalion level. This
simulation is stochastic and employs the event sequencing technique.

B. A full representation of combat effects is to be portrayed
within the simulation. Accordingly, a representation of Buppresaion
caused by both direct fire and indirect fire systems is to be generated.

C. This paper addresses the potential representation for the
indirect fire case. A definition of terms is given along with the
methodology proposed. The methodology described is a development of

a RARDE model on an analysis of British data on artillery effectiveness
from several allied invasions during World War II.

I I . DEFINITION OF SUPPRESSION

A. Suppression is often confused by being the result of two
phenomena, via, the fear of and reaction to a perceived threat caused
by the detonation of indirect fire munitions and the non-lethal physical
effects of the detonation of such munitions.

B. Within the AMSAA/RARDE combat simulation, these tvc phenomena

are to be separately represented, the former only being termed suppression.
The degradation of sensor systems caused by the dust and smoke of
artillery round detonation is tc be quantified and represented as a
separate effect.

C. Thu3, suppression is defined to be the effect cn a system caused
by the perception of a threat by that system's operators. The threat

in this paper will be taken to be the detonation of indirect fire
munit ions .

HI. DEFINITION OF SUPPRESSION EFFirTS

A. When a military system is suppressed, it is necessary to relate
this fact to ar. effect on that system's ability to undertake its intemied
functions in combat. Suppressitr. is not taken to mean that the system
becomes completely inoperable frr a period of time; the assumption made

is that a degradation in function performance results, each function being
affected in a different way.

B. The functions which it is contended will be effected are these
of detection, firing, and movement. These are discussed separately.

4Si

C . Detection

(

1. Three situations should he di f IVn-nt. i uted in this cut.<v.< >ry .
They are :

(a) A new detection generated from the normal search proc-c.r. •

(b) Retention of a previous detection.

The relationship of suppression effects to each of these three areas is
discussed separately since different considerations are necessary.

2. New Detection from Normal Search Process. When attempting

to detect targets the observer will, when suppressed, be unable to under¬
take the normal search process so efficiently. There will be periods
during which no observation is being made, but such periods are thought
not to be of significant duration. However, when suppression effects
become zero, the search process will be resumed at full efficiency.

The representation of suppression effects on this combat function
will be taken as a reduction in the detection rate parameter associated
with the log-normal distribution of time to detect. However, if the
suppression duration exceeds a specified maximum time, tmax, all
information collected on potential targets is lost, and all scheduled
detections must be cancelled.

3* Retention of a Previous Detection. In this case, the
representation to be used is that if the observer is suppressed for a
period of time exceeding +-max, as defined in Section III, Part C,
pa -agraph 2, the detection will be lost; reacquisition being made under
the normal search process or by launch signature detection.

The rationale behind this representation is that, after a
certain time period, the observer will have to reorientate himself tc
his area of responsibility, having lost his mental picture while being
suppressed.

b. Weapon Signature Detection. The detect i or. of a weapon
launch signature and acquisition of that weapon ur> a target can be
characterized as being stimulated by an awareness of a 'lash and/or
dust and Bmoke and, from this information which essentially restricts
an observer's search areu, characterized by detection from the resulting
search process.

ThUB, when a unit is suppressed, it is likely that the initial
cue of the flash and/or initial dust and nsioke cloud rrrwth will he less
readily observed. Although the dust and smoke cloud ray be visible,
the source point will not be so obvious resulting in the detection
being less likely.

The representation of this situation is proposed as a reduction
in the probability of detection when the observer is suppressed.

•181’

D. Firing

1. This situation occurs when the decision to engage a target
has been made and the loading and laying process is being undertaken.

2. It is unlikely that the loading phase of an engagement will
be affected by suppression since it is assumed that weapon systems in a
direct fire battle will be reloaded directly after undertaking an
engagement .

3. The laying process, however, may be affected since the crew
member responsible for this process can be suppressed. The effect is
likely to be a less accurate lay being achieved.

1*. Thus, the proposed characterization of suppression effects
is to be a reduction in the probability of hit, but no increase in the
time to complete the loading and laying process. The degradation in
hit probability will be a function of the level of suppression which
occurs. However, to prevent the situation arising in which a unit
fires many rounds with extremely low accuracy due to suppression
effects, an engagement is to be aborted if a threshold suppression
level is reached. This level is to be that at which a previous
detection is lost as described in Section 111, Part C, paragraph 3.
(Although Section III, Part C, paragraph 3 refers to suppression time,
it is possible to relate that time to a particular suppression level
since both suppression level and duration are calculated from the volley
density. Pee Parts B and C of Section V).

E. Movement

1. Two situations need to be differentiated in consideration
of this combat function. These are units which are moving and those
which are stationary.

(a) Stationary Units. The representation to be used in this
situation is that all stationary units remain in that Btate while
suppressed. For both defending units and attacking units in an over¬
watch role, it Is considered that they will remain at their location
and attempt to undertake their assigned missions while suppressed.

For attacking units in covered positions away from detectic-. by
enemy unite, it is assumed that they take a posture which reduces
suppression effects. Further, however, since they are in an out-of¬
combat state, they remain in this state until suppression effects cease
and may then rejoin the battle. The suppression effects in this case
are only those of delay on the suppressed units.

For units which have stopped to fire et the short halt during a
movement phase, they will be deemed to stop for as long as it takes tc
fire one munition and then to behave as a moving unit while encountering
suppression effects.

(

483

(b) Moving Units . A unit suffering suppression effects while
moving will be assumed to increase speed to it3 maximum and continue to
undertake its mission. If, however, a mixed unit of say tank:, and AFCs
is moving, the maximum speed is defined as the minimum of the maximum
speed of each constituent element in order that the unit maintains
cohesion.

The rationale here is that as much relief from suppression
effects may be gained by continuing towards a unit's objective as can
be obtained from any other course of action since the ease of re¬
direction of the deliverying artillery tubes' aim points is independent
of the moving units' direction of movement. Further, as the units close
with the enemy, the munitions causing the suppression may have to be
terminated to prevent damage to friendly forces.

IV. DIFFERENTIAL EFFECTS OF SUPPRESSION ON UNITS

A. Section III above describes the general way in which suppression
effects will be generated within the model and the rationale behind the
representation. However, no account was made of the difference in a
particular effect between different types of unitB. For example, a
tank will not be affected in the same way as an infantry squad when
searching for a target while under similar suppression conditions.
Moreover, the suppression effects will he a function of the actual
vehicle type as opposed to the generic vehicle class. For example,
an XM1 tank may be differently affected than an M60 tank simply because
of the design differences of the systems causing operation in a suppres¬
sion environment to be easier in certain cases.

B. In consequence, the methodology developed represents this
feature by a function suppressibility factor. ThiB factor is a function
of the vehicle/unit and varies with the individual functions described
in Section III.

C. To obtain values for this factor, it will be necessary to
investigate the processes by which the various unit, functions are
achieved.

1. The field of view of the sensor systems will be of
importance in this context since the visual cue of dt lon it.i rip art illery
munitions is likely to be the main stimulus for suppression.

2. Since suppression is likely to be affected by the vulner¬
ability of the unit to artillery munitions, this will also have to be
considered.

3. The ability to command a unit in a suppression environment
also will affect the factor. For a tank, the effect of operating in

a closed down or semi-closed down mode must be represented since the
commander will not be able to perform all of his functions r.c
efficiently under Buch conditions.

These are Just three of the areas to be considered in the generation
of value.’, for this parameter which are felt to be essential if a
supprer sii.'ti r- presentat i on which differentiates between vehicles within

a generic category and between different types of units is to be
generated.

V ’ METHODOLOGY

A . Representation of Indirect Fire Engagements

The method of representation of all indirect fire engagements is
that all consequent effects are assessed at the impact of each volley
fire and not as a total effect of a complete engagement. In conse¬
quence, suppression effects will be represented at the impact of each
volley.

The area which is affected by each volley is a number of 100
meter squares which are assessed for effect independently. Thus, a
munition detonating in one 100 meter square will have no effect on
an adjacent area. This methodology will apply similarly in the
suppression representation.

The volley density within a 100 meter square is the basis for
determining the suppressive effectB of the volley upon units in that
square. The precise methodology for calculating the suppressive
effects generated by a single volley is described in Section V,

Part B. A suppression time interval is also calculated and a
target will remain suppressed at the time level during this interval
unless another volley impacts in the vicinity of that target. If no
additional volleys are received, the target becomeB unsuppressed
at the end of that interval. Section V, Part C, describes the
method of obtaining the suppression time interval. As additional
volleys impact in the vicinity of a target, the cumulative effect
of those volleys is considered, as described in Section V, Part D.

B. Calculation of Suppressive Effect for a Single Volley

When a volley is delivered, the density of rounds in each 100 meter
square is determined. This density is then converted to standard units
(equivalent 105mm HE rounds) by multiploying by the lethal area of the
shells in the volley and by a conversion constant to represent the lethal
area of the 105mm HE round. This standardized density (d) is used to
define the suppressive effect of a volley (SE) by comparison with the
threshold at which initial suppression occurs (dj), as derived from the
World War II data used. The methodology is

SE ■ 0 if d dj (No Suppression)

SE' gTdT--- iV )' ~ X <«-*!> -a,

(Partial Suppression)

SE ■ 1 if i > 2dj - dj (Total Suppression)

485

■i

The commutation is simply the result of first assuming that
suppression increases linearly from 0 to 1 as density Increases from
dj to dj . Then, since the value PE will be assumed by the simulation
to remain constant for the duration of the suppression time interval ,
the calculated level is reduced by 50% to compensate for the actual
continuous reduction of suppressive effect which takes place during
the suppression time interval.

C. Duration of Suppressive Effects.

The duration (ts) during which the unit is suppressed, i.e.,
the time for the value of d to decay to dj, is calculated using the
assumption that the effects decay exponentially. That is

which yields

t# ■ - 1 In < d i /^ )

The constant a must be specified by input (assuming t * 30 for d ■
di + d2

- is a possible method for selecting the value of a).

D , Suppressive Effects of Subsequent Vol leys

Tie problem of determining the cumulative svippressive effect of two
or more volleys is addressed here.

Assume that the time of occurrence, t , and t he density, d^, of the
most recent volley with respect to a given unit are calculated. The
density, d, of the next volley, occurring at tlm t1, is calculated
independently as per Section V, Part B. This deneity is aecumula*. ei into
the residual effect of the previous volley to give an effective density,
d1, by

d « d + d

for At * t1 - t

- aAt

The value of SE is
and the duration of the

calculated from d1 as per Section V,
suppressive effects as per Part C.

Part 3

(

48<>

(

\ 'I

The following gruph represents a history of densities calculated
for several volleys. The length of the dotted line represents the actual
density of each volley.

Volleys are fired at times tQ, tj, t2* t3 and t*. The representation
above gives that the unit was partially suppressed from tj to tj,
tj to t|, t 3 to tj and totally suppressed from t| to t|. The value of

8E would be calculated as 1 for time t3 to tj, 0 from t0 to tj, tj

to t2> ti« to ts« and from ti and an intermediate value between these

times. Thus, if a value of SE was calculated at time t2, this level

of suppression effect would be assumed to stay for the period t2 to tj*

It should be noted that once a unit has been suppressed, it will always
have some residual density since a simple exponential decay is assumed.

.i f, v ; ivfl-.V

VI. APPLICATION OF SUPPRESSIVE EFFECTS. The suppressive effects ere
applied to the functions of the unit as described below and r-ummar i ?.ed

in the next table.

A. Detection

For a detection, the detection rate X, is reduced by the factor
(1-K.SE), SE as described in Section V (Part p) and K as described in
Section IV.

For a unit already detected, the detection is lost if tB
exceeds a specified value.

For a launch signature cue generated during the observer's
suppressed period, the probability of detection is reduced by the
factor, 1 - K.SE for K as specified in Section IV and PE as in
Section V (Part B).

B. Movement

All stationary units remain stationary for time tg. All
moving units accelerate to maximum speed for time t .

D. General

By selection of suitable value of K, the effect, of
suppression on a particular unit function may be net to zero.

SUMMARY OF SUPPRESSIVE EFFECTS

Detection rate ‘ Detection rate (1-K.SE)

Lost, if t > specified value
s

Detection prob -* Detection prob (l-K.SE)
P(HIT) V. (1-K.SE)

Remain in that state for time tg
Accelerate to max speed for time tg

DETECTION

(1) Future detection

(2) Already detected

(3) Launch signature

FIRING P(HIT) -►

MOVEMENT

(l) Stationary

(2) Moving

GROUND WARFARE DIVISION

INTERIM NOTE C-4S

REVIEW AND EVALUATION OF CURRENT
SUPPRESSION MODELS WITH PROPOSAL FOR INTERIM MODEL

Philip M. Allen

May 1977

Approved for public release; distribution unlimited

US ARMY MATERIEL SYSTEMS ANALYSIS ACTIVITY
ABERDEEN PROVING GROUND, MARY UNO

. . Vi. v, i ** Mi1 * ■» •

GROUND WARFARE DIVISION

INTERIM NOTE G-38

PMAl len/lfw

Aberdeen Proving Ground, MD
May 1977

UNCLASSIFIED ABSTRACT

A synopsis of several current suppression models and field
tests is presented together with an assessment of their relative
strengths and weaknesses. These sources are then combined to serve as I

a basis for formulating an interim suppression model to be used in j

existing high resolution force -on-force models. I

CONTENTS

Pa Re

ABSTRACT . 3

1. INTRODUCTION . 7

1.1 Objectives .

1.2 Background .

1.3 Scope . . .

2. REVIEW OF SOME EXISTING MODELS . 8

2.1 The Litton Model as Used in AMSWAG . 8

2.2 The RARDE Suppression Model . 1)

2.3 The CDEC Model . 10

2.4 The ASARS Model . 11

2.5 Revisions to the ASARS Model . 12

2.6 The DYNTACS Model . 13

2.7 The Naval Weapons Center Model . 14

2.8 The CARMONETTE Model . 14

2.9 The JIFFY Model . IS

2.10 Vector Research Proposal . 13

2.11 Proposal by Horrigan Analytics . 16

3. COMPARISONS OF EXISTING MODELS . lh

3.1 Direct Fire . 17

3.2 Indirect Fire . IS

4. PROPOSAL FOR AN INTERIM SUPPRESSION MODEL . 26

4.1 Direct Fire . 26

4.2 Indirect Fire . 26

5. RECOMMENDATIONS FOR FUTURE EFFORTS . 23

REFERENCES . 31

DISTRIBUTION . 33

REVIEW AND EVALUATION OF CURRENT
SUPPRESSION MODELS WITH PROPOSAL FOR INTERIM MODEL

. INTRODUCTION

1 . 1 Objectives.

One purpose of this study was to review the current models for
suppression, along with the data currently available, and combine this
information into a synopsis of each of the models and their relative
strengths and weaknesses. In connection with this objective, a meaning¬
ful comparison of the available models for realistic combat situations
was planned.

The second objective was to draw from the available sources a
model for recommendation as an interim suppression model to be implemented
into high resolution combat simulation programs. This model should be
revised or replaced as the general knowledge in the area of suppression
is extended and a greater volume of significant data is made available.

The development of the model was planned to include three major aspects
of the suppression phenomenon.

interval .

a. Probability of becoming suppressed in a given time

firing.

b. Effects of suppression on movement, acquisition, and

c. Duration of suppression.

1 . 2 Background.

There has been considerable interest recently in the modeling
of suppression, particularly since the release in April 1976, of data
from a series of field experiments on suppression conducted by the
US Army Combat Developments Experimentation Command (USACDEC) (Reference
1). The USACDEC data appeared to differ widely from the suppression
values predicted by the Litton model, which is currently being used in
the AMSAA War Game (AMSWAG) . Because of this and other questions about
the validity of the Litton model, there is a need to revise it or to
develop a new suppression model for implementation into AM5WAG. Since
there are several suppression models currently in use in other combat
simulation programs, there is also a need to evaluate them and make
comparisons of the values they predict for realistic combat assumptions.
The most desirable characteristics of each may then be determined and used
in any future modeling efforts.

1 . 3 Scope.

A major emphasis was placed on four of the models considered:

The Litton model, the Army Small Arms Requirement Study (ASARS) model,
the RAkDE model (developed by the Royal Armament Research and Development
Establishment of the United Kingdom), and the model developed from the

CDEC field test data. These were compared and evaluated extensively.
Other models were given less emphasis, and due to the unavailability of
detailed information on some of them they were not compared and evaluated
as completely. These include the suppression models used in DYNTACS ,
JIFFY, CARMONETTE, and the Naval Weapons Center combat simulation, and
models proposed by Horrigan Analytics and Vector Research, Inc.

Following the review and comparison of existing models, a new
suppression model was developed and recommended for use in AMSWAG. It
consists of a combination of the ASARS, CDEC, and RARDE models with
some modifications, as described in Section 4. The need to fill
gaps in the data on suppression was recognized, and recommendations are
made in Section 5 for filling those gaps.

2. REVIEW OF EXISTING MODELS

In this section a synopsis of each of several suppression
models used in various combat simulations (or proposed for implementation)
is given, with a brief assessment of their relative strengths and
weaknesses. Some of the descriptions are more general than others due
to the lack of detailed information available. Where possible, the
descriptions include the method of computation of suppression, the
effects of suppression, and the duration of suppression.

2.1 The Litton Model as Used in AMSWAG.

Probability of suppression, P(S) in the Litton model (Reference 2)
is a function of the expected fraction of casualties (f) during some time
interval At and a human factors coefficient (p) which is used to account
Cor individual variance in vulnerability to suppression. A value of 1.0
to p corresponds to the "average" soldier, with higher values of p corres-
tc more easily suppressed individuals and lower values corresponding to
individuals who are more difficult to suppress. Suppression of vehicles
has also been considered by using appropriately small values of p. The
formula for suppression is:

PCS) . 77-7 ,

Where 8 ■ 10 exp [(-0.04/p) (•

The Litton model itself does not predict the effects of
suppression or the duration of suppression. However, in AMSWAG
suppression affects firing (does not affect movement or acquisition) ,
The value of P(S) is interpreted as the fraction of a unit suppressed
That fraction of the unit continues to fire, but causes no attrition,
For duration of suppression, the following formula is used:

y - e

-At/us

where y is the probability that a suppressed unit remains suppressed
after time At and us is an input mean duration of suppression (usually
10 seconds for vehicles and 15 seconds for personnel).

A major advantage of the Litton model is that the inputs
required are simple and easily accessible. Also, the use of f takes
into account a variety of weapon and target characteristics. However,
the dependence of the model on f tends to make it extremely sensitive
to small changes in ? (e.g., for o ■ 1.0, as ? varies from .03 to .05,
P(S) varies from .11 to .47). Also, it is possible that two weapons
with similar effectiveness data would have different suppressive capa¬
bilities, due to aural and visual cues, but the Litton model would not
reflect such a difference.

2.2 The RARDE Suppression Model.

The RARDE/AMSAA model is a high resolution combat model being
developed jointly by AMSAA and RARDE, of the United Kingdom. The
information on the RARDE model was obtained from a published British
report (Reference 8), The suppression submodel developed by RARDE
considers direct fire suppression and indirect fire suppression separ¬
ately. For direct fire suppression of personnel, use of the Litton model is
proposed. Direct fire suppression of vehicles is caused by a lethal or
non-lethal hit on the vehicle. For indirect fire, it is assumed that
suppression is a function of the intensity of fire (I, measured in rounds/
hectre/minute) placed in the target area. The basis for the
equation used is a British report based on an analysis of WW1I data for
unprotected soldiers in which intensities of indirect fire required for
marginal suppression and for total neutralization were given, RARDE
converted these intensities to pounds of equivalent 105mm shells/100
meter square/min (I1) and arrived at the values of I'-.ll for the onset
of suppression and I' ".46 for total neutralization of unprotected
personnel. It is assumed that suppression exhibits a linear relationship
to 1' with P(S)»0(for I * • . 11 and P(S)»1 for l'»,46. The equation for
converting I to I involves the lethal area (LA) of the firing weapon
as follows:

I - I x (LA) x 1.06 x 10“3
The resulting equation for suppression is then:

P(S) - 2.857 x i'- .314, .11 < i' i .46

This value, P(S), is not actually called probability of suppression by
RARDE, but is instead, directly interpreted as the fractional reduction
in target acquisition, hit capability, and movement for dismounted in¬
fantry. For vehicles, a slightly different formula is used, based on
the same threshold intensities, but depending on the duration of bombard¬
ment. Target acquisition and movement are affected by indirect fire

"'I'-'. iftW f v “ Wriiuio.iA - ,v. 4* t

suppression of vehicles. The RARDE model also considers demoralization
for extremely intense bombardments of indirect fire on personnel.
Demoralization has the effect of prolonging the suppressive effects of
indirect fire.

An advantage of the RARDE model is that it distinguishes between
direct and indirect fire and models them differently. The inputs required
(fraction of casualties, lethal areas, and intensity of indirect fire)
are not extremely involved, and the equations are simple. However, the
use of linear relationships for indirect fire suppression may be open
to question, since no justification is made for that assumption.

2.3 The CDEC Model.

A series of field experiments was conducted by CDEC for both
direct fire and indirect fire suppression. Suppression was assumed to
follow a logarithmic function of the form

P(S) . J m (^) ,

where RMD is the radial miss distance of a given round. (Reference 1) .
A regression was performed from the field test data for each weapon
included in the experiment to determine the values of the parameters
A and B. Some examples of the values derived are as follows:

Direct Fire

M16A1 M60

M139 ■

41.724

42.719 89.556

160.940

674.37

-5. S49

-S .086 -5.395

-3.740

-4.860

Indirect Fire (Ground Burst)

60mm Mortar

81mm Mortar 4.

2 in Mortar

105mm Howitzer 8in Howitzer

65, 482

183.800

213.840

304,990 1120.78

-11.2799

-1.8674

-1.740

-1.8960 -2.1009

Indirect Fire (Air Burst)

4. Bin Mortar 105mm Howitzer 155mm Howitzer Sin Howitzer

274.10

278.30

366.14

1310.03

-1.60

-1.44

Since the experiments were designed only to measure probability
of suppression, the COEC model makes no predictions concerning effects or
duration of suppression.

The CDEC model is valuable, since it is derived from actual
test data. It also reflects the variation in suppressive capabilities
of different weapons more clearly than other models. However, there
are two serious limitations to its usefulness. First, the required
input of miss distance is not always easily accessible. Second, the
equations only apply to the weapons and conditions set forth in the
CDEC experiments (e.g., the only target posture considered was personnel
in foxholes with head and shoulders exposed) .

2 . 4 The ASARS Model.

The ASARS model (Reference 3) is unique in that it considers
seven suppression states, each of which is interpreted as a certain
percent degradation in firing, observation, and movement. The
suppression states are numbered 0 through 6 (0 ■ no suppression and
6 * total neutralization), and the percentage degradations in performance
for each state were derived from the results of a questionnaire adminis¬
tered to infantry organizations. The results are as follows:

Suppression State

Percent Degradation

Observe

Move

Fire

100

To determine the suppression state for an Individual
receiving fire, a binomial distribution (6,6) is assumed so that the
probability of an individual being in suppressed state X is

P(X«A)i

,, -,6-X*X where 0 is a function of
^ ' ’ the expected fraction of

...» i

casualties (?) associated with the firing event. By using data from a
perceived dangerousness experiment conducted by Litton (Reference 4) ,
the following relationship was obtained:

6 ■ 1.13 * 0.0527 In (?) o < ? < .085 *

Thus, the probability of attaining a given suppression level is
calculated as a function of ? and interpreted directly as a reduction in
efficiency of acquisition, movement, and firing. For duration of
suppression, it is assumed that a unit suppressed to level A will drop
to level A/2 after the next time interval in the ASARS Battle Model,

The ASARS model shares the favorable feature of the Litton
model that only ? is required as input. However, it appears to be
supported by experimental data more than the Litton model. (Responses
to questionnaires have confirmed the choice of a binomial distribution
for suppression states), and it provides for varying degradations of
the three functions of combat considered within each suppression state.

Of course, as was mentioned previously, any model which
relies on ? might fail to reflect properly the variance in suppressive
capabilities of different weapons. Another problem with the ASARS
model is in the development of the relationship between F and 0. The
data from which this relationship was derived shows a very poor
correlat ion.

Overall, the development of the ASARS model appears to be
mathematically sound, and it has potential value for predicting direct
fire suppression of infantry. For this reason, work has been done
to correct the problems stated in the preceding paragraph. The results
ar» described in the next section.

2.5 Revisions to the ASARS Model.

An effort has been made to improve upon the relationship
derived by ASARS to predict 8 from ?. Using the passive squad target
model developed at AMSAA, and choosing a medium range of 300 meters and
an engagement period of 20 seconds, values of ? were generated for the
weapons and rates of fire employed in the Litton perceived dangerousness
experiment. These were paired with values of 9 from the Litton experi¬
ment. (In the experiment, values of 9 were obtained for several miss
distances. These have been averaged to yield one 9 value for each
weapon and each rate of fire). A least squares linear regression was
performed on these data. The result was a much improved relationship
as given in the following equation:

0' ■ 1.633 + .2634 In (f) o< ? < .074 *

The correlation coefficient for this regression is 0.78, which is not
as high as desired, but significantly higher than the original relationship

For extremely small values of ? (which would permit 9/6' to be negative)
8/9' is defined to be 0 . Similarly, if ? > .085/. 074, 0/0' is defined
to be 1.

derived by ASARS (r - .6). As more data are obtained, a more accurate
relationship should be attainable.

There is also a need for the model to reflect the variance in
suppressive capabilities of weapons. This has been done by making use
of the CD EC suppression data. By comparing tho suppression values
predicted by the CDEC model for the direct fire weapons involved in the
CDEC experiments, adjustment factors were obtained, which indicate
roughly the ratio of probability of suppression for the given weapon
firing with a certain attrition rate (r) to probability of suppression
for the 7.62um> machinegun firing with the same attrition rate. The
factors obtained are as follows:

Weapon Factor

S.56ma Rifle 0.65
7.62mm Machinegun 1.00
.50 Caliber Machinegun 1.60
20mm Cannon 1.10
40mm Grenade Launcher 0.78

It should be noted that these factors are not intended to represent
directly the relative suppress iveness of the weapons, because they are
obtained for similar values of ?. (For example, the factor of 0.78 for
the 40mm grenade launcher does not imply that it is less suppressive
than the 7.62mm machinegun, because the 40mm grenade launcher generally
produces higher values of ? than the 7.62mm gun. However, in firing
events for which f values are similar, the machinegun should be more
suppressive). This factor is multiplied by 0' to produce 6, which is
used in the ASARS model as previously described. (For weapons not
included in the CDEC experiments, it must be assumed at present that
0'* 0). This method of calculating 6 should strengthen the ASARS model,
although it is recognized that there is a need to improve the method
further. Perhaps, as more data are received, it would be possible to
predict 6 as a function of some other variable or variables.

2.6 The DYNTACS Model.

In the DYNTACS model (Reference 5) suppression is dependent
upon the distance from a target to the impact of a round. For direct
fire, the round must hit or land directly in front of the target to
produce suppression. For indirect fire, an elliptical suppressive
region centered at the center of impact of a volley is input for each
weapon, round rnd target combinations. Any unit which lies in the
ellipse is suppressed. Suppressed units are unable to fire or acquire
targets, but movement is not degraded. The duration of suppression is
also provided as an input to the model.

This model achieves the desirable quality of simplicity at the
cost of a complicated set of inputs which are difficult to obtain and
may vary wiuely from one study to another. The DYNTACS model is limited
to use in Monte Carlo programs which model impacts of individual volleys.

2.7 The Naval Weapons Center Model,

The model developed by the Naval Weapons Center (Reference 6)
is similar to the DYNTACS model in that targets are suppressed if they
are within the suppression region surrounding the impact of a round.

Here the suppression region is defined by contours which we speci¬
fied by input. Also, the Naval Weapons Center model is much more
sophisticated. A target can be in one of three suppressed states,
depending upon the proximity of the round impact. If the target is
inside the .001 Pv contour (a region around the center of impact of a
round inside which the probability of kill is greater than or equal
to .001), it is placed in the first suppressed state. Inside the .01 P^
contour targets are suppressed to the second state, and inside the .1
Pjt contour suppression state three is reached. The only difference in
the three states is the recovery time. In the first state Csi) , a
target will become unsuppressed (provided no new fire is received)
after the next battle interval (S to 10 seconds) , whereas targets in
state two (S2) remain suppressed for two periods, and in state three
suppression is maintained for three battle periods. A Markov chain
is used to determine the suppressed state of a target in successive
time intervals with units moving up or down in suppressed states,
depending on the proximity and lethality of future rounds.

Another unique feature of the Naval Weapons Center model is
that suppressed targets are less vulnerable and, therefore, have lower
PK's than when unsuppressed. Most of the models considered in this
report do not reduce the vulnerability of a suppressed target.

The model makes no effort to predict effects of suppression.
Instead, the fraction of time a target is suppressed or incapacitated
is computed as a measure of effectiveness of a mission. The choice of
threshold P]< values of .001, .01, and .1 is crucial to the Naval Weapons
Center model. Although a limited effort has been made to justify the
values chosen, they may still be open 10 question.

2.8 The CARMONETTE Model.

Suppression in CARMONETTE (Reference 3) is very similar to
DYNTACS. A target is suppressed when a certain amount of fire is
received within a designated time interval (commonly 60 seconds) in a
region surrounding the target. The amount of fire required to produce
suppression is measured in neutralization weights per grid square

containing the target. These are provided as input for each target
as well as an impact area of suppression and a neutralization weight
per round for each weapon,

Two levels of suppression may be achieved, depending on the
neutralization weights per grid square delivered. A target may be
"pinned down", resulting in an inability to move and reduced acquisition
and firing effectiveness. The target may be "partially neutralized",
in which case weapon accuracy is SOS degraded, aiming time is doubled,
acquisition is reduced 2si and movement is slowed.

As an example, in one study a neutralization weight per
round of 15 was input together with an impact area of 300 X 300 meters
for the 155mm Howitzer. For dismounted troops, the values of 200 and 143
neutralization weights per grid square were input as threshold values
for the units to be "pinned down" and "partially neutralized",
respectively. Hence, 10 rounds of 155mm projectiles delivered per
grid square per minute will partially neutralize troops within 150
meters of the center of impact, and 14 rounds per minute will keep them
pinned down.

CARMONETTE shares with the Naval Weapons Center model a
reduced vulnerability to fire for suppressed units. In CARMONETTE a
suppressor, infintry unit is S0% less exposed.

The inputs required for CARMONETTE are numerous, and the
method of selecting values of those inputs appears to be rather
arbitrary. Inputs which are readily obtainable from available data
would be more favorable.

2.9 The JIFFY Model.

The JIFFY model (Reference S) computes suppression from the
firepower score of each weapon. The firepower score is adjusted
according to type of engagement, and ratios of attacker to defender
firepower are computed for maneuver weapons and for support weapons.

A table of suppression probabilities associated with firepower ratios is
input, and the suppression value for the appropriate firepower ratio is
extracted. The probability of suppression is directly interpreted as
a fractional reduction in enemy weapons killed.

The JIFFY model, like CARMONETTE and DYNTACS, relies heavily
on input. The basis for the table of suppression values used in JIFFY
is unclear. According to Willis (Reference 4), the source seems to be
judgmental .

2.10 Vector Research Proposal.

Vector Research introduced in April 1975 (Reference 7) a
suppression model for possible implementation into the TRASANA AIDM

(AMSAA Improved Differential Model). The Vector proposal includes a
lenghty discussion of numerous equations for the effects of suppression,
with units being transferred from suppressed to unsuppressed groups and
vice versa, so that acquisition, vulnerability, etc., may be computed
separately from units in suppressed groups and units in unsuppressed
groups. However, the entire model is based upon computing a single
round probability of suppression and accumulating that for all rounds
and all weapons firing at a given target. The single round probability
of suppression (S) is calculated as a function of probability of a non-
lethal hit (NIH) and probability of a near miss (NM). The following
formula is used:

P(S) - P(S/NLH)XP(NLH) + P (S/NM)XP (NM)

P(NLH) and P(NM) are computed in the program, but P(S/NLH) and P(S/NM)
must be provided as input. Furthermore, a suppressive area must be
defined, before P(NM) can be calculated. Thus, a user would need
essentially to know the probability of suppression for each weapon and
target combination before using the suppression model. The value of
the model is, therefore, questionable.

2.11 Proposal by Horrlgan Analytics.

Horrigan Analytics has proposed a model for expected duration
of suppressive effect and detection time while under suppressive fire.
(Information was obtained from an unpublished report by Timothy J.
Horrigan of Horrigan Analytics titled, "Detection in the Presence of
Nonuniform, Mixed Suppressive Fires). A formula for duration of
suppression as a function of constant single -round duration of
suppression and the intensity of fire is given, and a corresponding
formula for expected detection time is developed, Then these formulas
are revised to allow for the single round duration of suppression to
be considered as a function of miss distance, and to consider any mixture
of projectile types fired. Finally, the model is generalized to consider
fractional suppression,

This model is only concerned with duration of suppression and
detection time. No effort is made to predict the probability of
becoming suppressed or the effect of suppression on movement or firing
efficiency.

3. COMPARISONS OF EXISTING MODELS

Comparisons have been made for five of the models
discussed in the previous section. The Litton, CDEC and ASARS direct
fire models are compared, and the Litton, RARDE, CDEC and DYNTACS
models for indirect fire and compared. The DYNTACS comparison is
limited to the lS5ma Howitzer, since that is the only weapon for which
data were available. The other models are excluded due to a lack of data
available or an Inability to establish a basis for comparison.

Clearly, it is impossible to obtain pure, straightforward
comparisons of the models, since each is based on different assumptions
about the nature of suppression. It should be noted, then, that certain
assumptions must be made in order to put the models on common ground.

These assumptions are described for each comparison constructed, and any
evaluation of the comparisons should be made in consideration of those
assumptions.

3.1 Direct Fire.

The passive squad target model developed at AMSAA's Ground
Warfare Division was used to generate expected fraction of casualties
(?) and radial miss distances for 20 second engagements against a squad
of eight men. The squad is randomly located m a SO meter wide area
and in foxholes with head and shoulders exposed. The firing technique
was to sweep across the target area firing single bursts at pre-determined
aim points. A matrix of weapons, ranges, number of aim points and rounds
per burst employed is given below:

Weapon

Range

Aim Points

Rounds /Burst

5 .S6mm rifle

100

300

SOO

7.62 mm

200

machinegun

400

600

900

1200

20mm cannon

400

' S

800

1200

1600

SO cal

400

machinegun

800

1600

40mm grenade

400

launcher

800

1200

1600

- 1

The value of ? was used to compute suppression by the Litton
model (with p ■ 1.0) and the ASARS model (using the revised relation*
ship between i and 8, as described in Section 2.S). Since probability
of suppression is not computed in ASARS, the values given are the
calculated fractional reductions in efficiency of observation, movement

and firing. The average radial miss distance for the rounds of each
burst (in the vertical plane of the target) from each man was used to
obtain a probability of suppression by the CDEC model, which was
accumulated for all bursts fired. Thus, for K bursts fired, if 5, is
the probability of suppression for burst i, then the accumulated 1
probability of suppression is:

PCS) - l - [i-P(S4)]

The complete results are shown in Table 1, with sample graphs of
suppression as a function of range for three of the weapons given in
Figures 1, 2 and 3.

3.2 Indirect Fire.

A comparison of the Litton, CDEC, and RARDE models for
indirect fire suppression was made, using delivery accuracies and
effectiveness data from the Joint Munitions Effectiveness Manual (JMEM) .
Weapons considered were the 81mm mortar, 105mm Howitzer and 155mm
Howitzer, firing HE projectiles with both air and ground bursts. Two
delivery techniques were chosen. An effort was made to use tactically
realistic rates of fire, ranges, and battery formations. The target
was assumed to be prone personnel in open terrain.

Litton suppression values were calculated directly from JMEM
casualty data for the target radii selected. To facilitate computation
of RARDE and CDEC values, the target area was divided into 100 meter
squares, with one individual assumed to be located in the center of
each square, Delivery accuracies were used to calculate the probability
of a round landing in each square. Thus, an intensity of fire in each
square was obtained (assuming a certain time period for the firing
event) and used in the RARDE model. An average miss distance from each
individual in the target area was estimated for rounds landing in any
given square, so that probability of suppression by the CDEC model could
be calculated and accumulated over all squares for each weapon in the
battery.

The complete results of these computations are shown in
Table 2, with sample graphs in Figures 4, 5, 6 and 7. These comparisons
should only be considered as rough estimates due to averaging required
in computation of CDEC and RARDE values.

A similar comparison was attempted for DYNTACS, LITTON and
RARDE, However, in DYNTACS suppression probabilities are not computed.
Instead, an elliptical suppressive region is input, and targets lying
within it are suppressed. Input values of 170 for lateral radius and
70 for forward radius were obtained for the suppressive region for a
155mm Howitzer firing an HE projectile, ground burst. A probability of
suppression was generated by taking the ratio of individuals in the
target region (located at the center of each square) who are in the

flea** Ok

TARGET RADIUS (METERS}

Figure 4, Indirect Fire Suppression - 105MM Howitzer
1 Vtolley, Air Burst, Met+Ve Technique.

-liLu i/tor.iiibi'ii {-uJjAi5ifc.tA.-o

r-t/fc

Jl'

•M

TARGET RADIUS (METERS)

Figure 6. Indirect Fire Suppression- 105MM Howitzer
Air Burst, 1 Volley, Observer Adjusted.

T ^

. Howitxtr

Fir.

suppressive region to the total number of individuals m the target
area, An illustration for a 300 X 300 meter target area is shown in
Figure 8. ft may be observed that three of the nine individual- m
the target area lie within the suppressive ellipse. rims, the proL.ii-i 1 :
of suppression is calculated to be .33, (It may be more accurately term :
the fraction of the target suppressed.) A table of the suppression
values is also given in Figure 8.

It should be emphasised that the values obtained in these
comparisons can not be taken as completely accurate. Because of the
extreme difference in the nature of the models compared, assumptions,
as described above, were required, which could lead to some computationa
inaccuracies. However, these comparisons should provide some insight as
the relation of the models to one another.

4. PROPOSAL FOR AN INTERIM SUPPRESSION MODEL

From examining the models and the nature of suppression, it
appears that suppression should be divided into direct fire and indirect
fire suppression, each of which snould be subdivided into suppression
of personnel and suppression of vehicles. Any model for suppression
should consider all these areas separately. The proposals for modeling
indirect fire and direct fire suppression of personnel and vehicles
are given in the next two sections.

4.1 Direct Fire.

For direct fire against personnel, the ASARS model with the
revision, and inclusion of the CDEC data, as given in Section 1 , 3 is
proposed. The validity of the binomial distribution has been confirmed
by empirical data, and it allows for varied degradation in performance
of the functions of combat without relying on arbitrary inputs or
extremely complicated formulas. It is based directly on empirical data,
an area in which most other suppression models are lacking. Also, the
calculation of 8 could be adjusted as more data are received without
affecting the development of the model.

For direct fire against vehicle orews it seems reasonable to
adapt the criterion that a direct hit can Cause suppression. Therefore,
it is proposed that the probability of suppression be equated to the
probability of a hit for vehicles. Acquisition and movement should be
degraded for suppressed vehicles.

4.2 Indirect Fire

The RARDE model is recommended for indirect fire suppression.
It considers personnel and vehicles separately, although the methodology
is similar. The RARDE model is shown in the comparison to predict
values between the values of Litton and CDEC which in itself is no
justification. However, the modeling of indirect fire suppression as a
function of intensity of fire is intuitively

3COM

* - LOCATION OF PERSONNEL IN TARGET AREA.

Probability of Suppression

Delivery

Target

One Volley (Six Rounds)

Technique

Radius

Litton

RAUDB

DYNTACS

Observer

SOa

.75

1.0

Adjusted

150a

.27

.SS

.33

Rang*: 10,000a

Tias : 30 Seconds

Battery of 6 in ia:y w Formation

Open terrain; ground burst

Target: Prone personnel

Figure 8. Indirect Fire.’ DYNTACS Comparison 155 MM
Howitzer.

appealing, and by using lathal areas to dafina intensity of fire, the
model acquires a favorable responsiveness to variations in weapon types,
target posture, terrain and other variables. Lethal areas are available
for most weapons and conditions, and the intensity of fire is not difficult
to calculate.

It is believed that the use of the model proposed here would
significantly improve thj quality of the representation of suppression in
AMSWAG, and other combat simulations, More precise models may be
developed as the nature of suppression becomes better understood.

5. RECOMMENDATIONS FOR FUTURE EFFORTS

Any improvements in the modeling of suppression depend upon
the collection and analysis of meaningful suppression data. Objective
experimental data are desirable, but not easily obtained. Delphi studies
can be very valuable, provided the sample is large and not biased. Two
specific recommendations for data collection are made here:

a. A field experiment similar to the one conducted by Litton
on perceived dangerousness should be conducted, using a greater variety
of weapons and a larger number of trials, in order to validate or improve
upon the relationship developed between f and d in the ASARS model.

Also, the participants should be given descriptions of the suppression
states defined in the ASARS model. They could then be asked to associate
the fire received in each trial with one of the suppression levels
rather than with the vague notion of dangerousness.

b. Delphi studies should be conducted to validate (or
invalidate) the percentage degradations of observation, movement and
firing in the suppression states of ASARS, and the choices of
threshold intensities and associated movement and acquisition reductions
in the RARDE indirect fire model. A sufficient number of responses from
a cross-section of individuals should confirm the values suggested or
strongly establish new values. It is believed that the data from these
efforts will greatly enhance the modeling of suppression and make
progress toward putting it on a solid basis of empirical data.

TABLE 1. DIRECT FIRE SUPPRESSION

table L. imhrect fire suppression

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REFERENCES

1. Suppression Experimentation Data Analysis Report, April 1976;

United States Army Combat beveiopments Experimentation Command, Fort
Ord, California; UNCLASSIFIED.

2. Winter, Ralph P. and Clovis, E. Robert; Relationship of Supporting
Weipon Systems Performance Characteristics to Suppression of 'Individuals
and Small Units; tR-73/002, January 1973; Defense Sciences laboratory,

Mel ionics Systems Developments Division, Litton Systems, Inc., for the
U. S. Army Combat Developments Command, Infantry Agency, Fort Benning,
Georgia (Contract NO. DAAG0S-72-C-0471) ; UNCLASSIFIED.

3. Riddel, Major John M., Modeling of Suppression in the ASARS Battle
Model; United States Army Infantry School .

4. Kushnick, S. A. and Duffy, J.O., The Identification of Objective
Relationships Between Small Arms Fire Characteristics and Effectiveness
of Suppressive Eire; TF 72/lo62, April 197$; Defense Sciences Laboratory,
Sunnyvale, California; CONFIDENTIAL.

5. Willis, Roger F., Existing Models of Suppression and Their Under¬
lying Assumptions; U. S. Army TRADbC Systems Analysis Activity, White
Sands Missile Range, New Mexico; taken from Proceedings of the Four¬
teenth Annual U. S. Army Operations Research Symposium, 17 November

- 20 November 1975, Fort Lee, Virginia; UNCLASSIFIED.

6. Kinney, Douglas G., Modeling of Weapon Suppression Effects; February
1974; NWCTP 5620; Weapons Planning Group; Naval Weapons Center, China
Lake, California; UNCLASSIFIED.

7. The Representation of Suppression in the TRASANA AIDM; BDM/CARAF-TR-
75-049, April W5; Vector Research, Inc., Leavenworth, Kansas (Contract
No. DAAG 39-74-C-0018 , Task Order 7-75); UNCLASSIFIED.

8. Cran, George C. , Minefield and Barrier Combat Simulation - Suppression
Model ; Royal Armament Research and Development Establishment (RAkDE) Branch
Memorandum 17/76 (MA2); United Kingdom; CONFIDENTIAL.

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APPENDIX E

Suppressive Effects of Artillery Fire
By

F.W. Niedenfuhr (MITRE Corporation for DARCOM)

SUPPRESSIVE EFFECTS
OF ARTILLERY FIRE1

F. W. NIEDENFUHR

The MITRE Corporation
Washington C^ Operations
McLean, Virginia

For presentation at the Fire Suppression Symposium
U.S. Army Field Artillery School, Ft. Sill, Oklahoma
24-25 July 1979

^Results reported! here were obtained in the course of a study
entitled Counterfire Campaign Analysis, conducted by The MITRE
Corporation under sponsorship of the Directorate of Battlefield
Systems Integration, U. S. Army Materiel Development and Readiness
Command, Contract. No. F 19628-79-C0001

ABSTRACT

Some definitions of suppression are suggested and
formulas are proposed for the suppression and attrition
of cannon artillery batteries. These show the dependence
of suppressive effects on both technological and be¬
havioral parameters. Results from combat modeling and
simulation are introduced to illuminate the impact of
suppression by counterfire on the central battle.

Scenario dependent effects are discussed.

1.0 INTRODUCTION

The analysis of suppressive effects has proved to be neither simple
nor definitive, as is attested by the proliferation of measures and models
of suppression. It is apparent that the problem is not nearly as well in
hand as is, say, the problem of calculating weapons effects. Indeed, many
more insights need to be developed before a definitive view of suppression
can be attained. The writer hopes that this symposium will prove to be a
positive step in this direction; it is by no means obvious, however, that
the final answers will emerge here or even in the near future. Experimenta¬
tion and innovation are to be encouraged.

In this paper we use the term MippieMion in the sense of a temporary
or transient reduction of an opponent's ability to be productive. Permanent
reductions in the opponent's productivity are said to be due to £ttttcti.on,
and we take the point of view that it is the fear of attrition that causes
suppression. We postulate, however, not an irrational fear of attrition,
but an enlightened, experienced, or battle-wise fear. Thus, suppression is
taken to be a loss of productivity due to evasive action to avoid attrition.

It is not possible to say with certainty exactly how human beings will
behave under any given circumstances. It is possible, however, to investi¬
gate the consequences - in terms of attrition and productivity - of various
alternative behaviors. Having done this, one can identify the behavioral
path which is most advantageous. In combat modeling, we select that be¬
havioral path which leads to minimum attrition or maximum combat productivity,
according to the urgency of the combat situation. Thus, while it is not true
that humans iviCC select an optimal behavior path, we believe that in the

the long run most people will learn to avoid the aversive consequences of
non-optimal behavior.

It is better to be lucky than wise. Some weapon crews will be lucky,
living and maintaining productivity despite a hail of lethal incoming fire.
Being lucky, they never learn; they never need to learn. Analysis cannot
say much about such people, except that there will be few of them. Analysis,
however, can describe those fellows who do not live u charmed life, and it
is to them that we devote our attention here. We idealise their options
by postulating that, at any given time, they exist in one of two mutually
exclusive states: either a state in which they are productive but vulnerable
(i.e., have a given probability, Pj, of being killed by an incoming volley)
or a state in which they cannot be productive but have a lesser probability,
P2, of being killed when a volley arrives. Qualitatively, one says that
units are suppressed to the extent that their integrated productivity is
reduced because they have elected - or been forced - to remain in the
second state for *t least part of the time,

These ideas would seem to be applicable to a variety of combat situations
all that is necessary is to be able to define the states, their associated
kill probabilities, and the intended product of the suppressed units. Ma¬
neuvering units may have their product measured in terms of kilometers of
advance; command centers have a product which might be measured in terms of
message units; and artillery units have volleys fired as a natural product
to measure. The states and associated kill probabilities are obviously
also different for different types of units. Thus, the analysis of sup¬
pressive effects is necessarily scenario dependent because different victim
units have different productivities and can take different types of evasive

action. Suppressing tactics can also vary through choices of weapon,
munition, frequency, and duration of suppressive fire.

In the body of this paper, we specialize to consider suppression of
cannon artillery units by other cannon artillery units. Even here it is
necessary to divide the work into two parts, according to whether the
victim weapons are towed pieces or armored solf-propelled. The natural
units to consider are batteries, because they consist of elements which
have a high degree of behavioral coherance due to the command structure
and because each of these elements is subjected to approximately the same
degree of risk at the same time.

2.0 FACTORS CONTROLLED BY THE SUPPRESSOR

The suppressor is presumed here to have target location data and to
fire standard parallel sheaf volleys which provide reasonably uniform lethal
coverage of the victim's battery area. The fractional damage per volley
can be computed In a straight forward manner by standard weapon effective¬
ness techniques, accounting for target location error, weapon precision
and bias errors, and the munition lethality. Towed weapon crews can be
assumed to get some protection from their weapon itself as well as from
Its revetment, so their vulnerability is taken as equivalent to that of
prone troops. Typical results for single volley fire at midrange by U.S.
eight-inch howitzer batteries are given in Table I.

TABLE I

Typical Expected Fractional Damage

Target Element

Munition Type

DP I CM

SP Weapons

.002

.015

Towed Weapons

.001

,005

Towed Weapon Crews

.030

.200

Troups in Foxholes

.005

Beside the munition and weapon type, the suppressor has a choice of
the duration of the action he takes and the number and frequency of suppressing
volleys fired over this period. Maximum attrition is generally achieved by
massed fire which takes the victim by surprise, but when many single battery
volleys are fired in sequence, the first provides a warning and subsequent
volleys may act only on troops who have found shelter in convenient foxholes.
For an action which takes place over many minutes, there is a question of how
best to distribute the suppressing volleys in time. Rapid fire may be wasteful
of ammunition for the reason just noted, while slow regular periodic fire gives
away too much information; the victim could soon learn to take advantage of
regular lapses between volleys. It seems reasonable, therefore, to avoid
these problems by randomising the suppressive volley arrival times so that
the victim is encouraged to keep his head down because he cannot predict
when the next volley will land. For analytical purposes, it is convenient
to represent this type of suppressive fire by a Poisson distribution with
a parameter X which represents the average rate of suppressive volley fire.

Then the probability that n suppressive volleys will arrive in a time period
of duration T is given by Equation (1).

„ _(xT)n -vr

pn " T) e

1 1)

aiAi

In particular, the probability that no suppressive volleys arrive in time T
- vT

is c , ami the expected number of volleys in time T is XT.

3.0 FACTORS CONTROLLED BY THE VICTIM

The victim controls his response to incoming fire. For towed artillery
batteries engaged in a mission, the victim can opt for one of two states:
o Continue firing his mission and accept whatever attrition
results, or

o Switch to a non-productive state. There are two ways of doing this:

- Vacate the position

- Seek cover in foxholes '

Armored self-propelled weapons, in particular Soviet weapons, which can fire
with the crew on board, generally will not utilise the second way of becoming
non-productive. Although it is safest for the personnel, the weapons them¬
selves are still subject to attrition, and it turns out that vacating the
position is the better tactic.

3.1 TOWED UNITS WHICH STAY IN THEIR POSITION

Towed units which do not vacate their firing position can pass back
and forth between the protected and productive states. For example, if the
average interarrival time of suppressing volleys is long, the suppressed
unit could achieve some productivity by coming up out of its foxholes as
soon as a volley lands, firing its own weapons for some time, and then
returning to foxholes to await the next suppressive volley. We can account
for this behavior by defining a duty cycle parameter, a, such that the
suppressed unit spends an average time of a/X in the productive vulnerable
state and (l-c«)/.\ in the protected state during each interarrival period.

The value a-0 corresponds to always staying in the protected state, while
a»l means always staying in the vulnerable state; intermediate values cor¬
respond to the mixed strategy.

to his instantaneous unit strength. E.g., it would take twice as long to
deliver a number of full volleys when the victim is at half strength as it
would at full strength.

Assuming that the victim unit could deliver one full strength volley
each z\ minutes if unopposed and at full strength, it could then deliver
volleys in the (n+l)st interarrival period if it is in the productive
state for a fraction, a , of this period:

It follows that during N periods of length X’1 , the expected total number
of volleys that could be delivered by the victim unit is

(7)

where q is from Equation (S). Further, counting the victim's original
strength as unity, the expected residual strength at the end of the N
periods Is

s ■ q (8)

If unsuppressed, the victim could deliver N/Xti volleys in this time, so
that wo may define the supple S-icd ^ctivnaJL productivity (SFP) as

SFP * Q/(N/Xt!)

(9)

It is seen that SFP ■ 0 fora* 0 (victim always stays in the protected
state), and SFP is given by Equation (10)for a * 1 (victim always stays in

the vulnerable protected state.)

When a ■ 0, the victims remaining fractional strength after N periods is

-NP-i -NPi

e and when a ■ 1 , the remaining fractional strength is e L.

Thus far we have been concentrating on the case of a towed artillery
victim battery, exercising the options of switching between a protected non¬
productive state (e.g. in foxholes) and a vulnerable productive state, The
formulas (8) and (9) make it possible to estimate the attrition and pro¬
ductivity of the victim in this case as a function of his behavioral response
to suppressive fire. Figure 1 nhows the results of sample calculations for
a specific case: N • 10 suppressing volleys fired on a random schedule at
an average interval of five minutes, t\ * .5 minutes, and from Table I,

Pi « .200, P2 ■ .005 for DPICM, and Pj = .030, P2 = .005 for HE as the
suppressive munition. Note how suppression and attrition are interrelated -
as the victim acts to preserve his manpower (a-*0) his productivity is vastly
reduced. The relative effectiveness of DPICM and HR is also clearly evident;
one can imagine that in an urgent combat situation, the victim might elect
to accept the attrition forced on him by manning his weapons continuously
when under fire by HE, but it is doubtful if he could adopt this tactic
under suppresion by DPICM.

Remaining Fractional Suppressed Fractional

Strength . Productivity (SFP)

Figure I

Dependence on Duty Cycle Parameter, a

3.2 VACATING A POSITION UNDER FIRE

We have seen that the probability of surviving for time T under

randomly timed volleys each of which yields a kill probability P is

exp - (APT). If P » P(t), it is easy to show that this expression becomes

exp

-(xjp< tjdt)

This is the situation when a unit vacates a position under fire. During the
preparation for a move P(t) ■ Pj , but when leaving the position P(t) decreases
steadily as the unit moves away from the center of the target and approaches zero
as the unit gains a safe distance. The relation between the geographical and
temporal distribution of the kill probability P depends on how long the unit
takes to prepare to move out (tp) and how fast it moves once it gets under
way (V) .

Numerous calculations of the geographical distribution of P show that
it looks much like a flat Gaussian distribution which becomes essentially
zero at distances of about five hundred meters from the target center. A
reasonab’e approximation for P(t) is to take it as constant for tgtp antl
linearly decreasing to zero for tp<;t£tR+ t , where tR » R/V, and R is the
distance (500 m) from the target center at which the kill probability es-

sentially vanishes. With V measured in kilometers per minute, then Equation
(11) becomes

q « exp - A P >(t + 1/4V] U-)

In Equation (12) , q approximates the surviving fraction of a unit which
vacates a position under fire, given that it was at full strength when the
evacuation began. If the unit begins the evacuation at less than full
strength, Equation (12) simply gives the proportional reduction.

3.3 ESTIMATING HOW LONG 10 STAY IN THE PROTECTED STATE .

Suppose the victim unit elects to take cover in foxholes and stay
there until the suppressive action terminates. It seems reasonable to postul
that when the victim unit has waited a long time without receiving any in¬
coming rounds it should be safe to conclude that the suppression has lifted.
But how long is "long"? The question can be rephrased in terms of the

additional risk incurred by acting on the assumption that the suppression

has indeed lifted.

Consider the case in which the suppressed unit is called upon to fire
a mission of duration tm. If the suppressive fire has not lifted, the pro¬
bability of surviving for this length of time in the productive state is
e”Xf>ltm and e"XP2r'm in the protected state. If tho suppressive action has
terminated (and does not resume) tho survival probability is unity in either
state. Thus if the unit moves to the productive state and performs its

mission, its probability of surviving for time t is

P * Pse"XPltm + (1-Pg) ‘ * > (13)

and if it remains in the protected position, its probability of surviving
for this time is

P' ■ Pso'XP?tm ♦ (1-P^) .1 , IN)

where P^ is the probability that the suppression has not lifted. The
second course of action is safer but not productive. Let a denote the
additional risk due to chasing to fire the mission, i.e., '■ = P’- P.

In order to quantify <5, it is necessary to have estimates of \ and P ;
these can be obtained as follows: For \, wo can suppose that the victim

unit knows that it has beer under suppression for a time T and in this
time has received N suppressive volleys. (Even a subjective estimate of
T and N should suffice.) Then,

X s* N/T (15)

Now imagine that the period T is followed by an observation period of
duration t in which there is no incoming fire. The probability of this
occurrence is (cf . Equation (1) with n ■ 0)

Po* e‘Uo (16)

If XtQ is large, is small, i.e., it is unlikely that a period as long
as t occurs in the Poisson process under consideration. We interpret
this state of affairs as equivalent to the likelihood that the process is,
in fact, continuing. I.e., for small pQ ,

Ps* po.e’Xto . (17)

Then combining Equations (13) through (17), we find

1 n o rc - o in

(18)

That is, given X, t , Pj , and Pj , we can solve for t , the time to wait
m o

with no incoming fire in order that an additional risk 6 is incurred by deciding

to move into the productive state and fire the mission.

Analysis shows that (\t ) as a function of (Xt ) as expressed in

o m

Equation (18) has a very broad maximum; it is essentially constant for values
ot J ;,ud 100, and this is the range of practical interest.

Inu magnitude ui tins constant maximum value oi (xt j, depends on < and
shows that the additional risk incurred by deciding to come out of the
protected state and fire the mission is less than two per cent for values of
(AtQ) greater than four. This conclusion leads to a useful result, namely
an estimate of the time we may expect a suppressive action to be effective.
The suppressed time is approximately the time taken to fire the suppressing
volleys plus four interarrival times.* Victim units which remain suppressed
for longer than this are behaving very conservatively while those which stay
in the protected state much less than this will suffer a non-negligible
amount of attrition.

Ts»T ♦ 4/X (19)

In Equation (19) T is the suppression time, T is the actual time duration
of the suppressive fire, and A"1 is the average interarrival time of ran¬
domly spaced suppressive volleys. No estimate of suppression time is
completely accurate, of course, but the criterion developed here seems more
reasonable than such bald assumptions as "Suppressed units will stay In
foxholes for thirty minutes after the last volley impacts."

4.0 EXAMPLES OF SUPPRESSION UNDER RANDOM INTERVAL VOLLEYS

We can use the ideas outlined in the preceding sections to construct
estimates of the consequences of various courses of action by either the
suppressor or the suppressed. As a first example, consider suppression of
a towed battery by DPICM volleys fired under a Poisson schedule with an
average interarrival time of five minutes. The victim battery could fire
one volley each minute if unopposed and at full strength. Pi and P2 are

* Provided, of course, that the suppressing volleys are too lethal to ignore.

taken from Table I, and it is assumed that the initial volley catches the
victim in his unprotected condition. Figure 2 shows the time trends for
various choices of the duty cycle parameter, a. It is clear that the unit
which wishes to live to fight again should behave conservatively and defer
firing its mission until the suppressive effort has lifted.

The next example further illustrates the possible consequences o'- s

alternate behaviors on the part of the suppressed unit. Suppose that the ^

victim battery has an assigned mission of delivering 6,500 kg of projectiles
as rapidly as possible. Just as it begins this effort, random suppressive
fire initiates and lasts for fifteen minutes. The victim battery can either
fire its mission and then vacate the position or shift its firing point half
a kilometer and then fire its mission, or if it does not have armored weapons,
men can take cover in foxholes till they are "sure" the suppression has lifted
and then fire their mission. (In this last option, they use the 4/\ criterion
of the previous section.) Table II gives the results of calculations based
on the equations given in Section 3 and estimated performance parameters for
the weapons involved.

TABLE II

EFFECTS OF FIFTEEN-MINUTE SUPPRESSION MISSIONS

SUPPRESSOR1

VICTIM

WEAPON

MISSION2

RESPONSE

MISSION TIME

ATTRITION

M110 A-2

152 SP

25 VOLLEYS

SCOOT THEN SHOOT

14 MINS

WITH DPICM

(10 MINS,

SHOOT THEN SCOOT

11 MINS

M110 A-2

D-30

50 VOLLEYS

SCOOT THEN SHOOT

23 MINS

21%

WITH DPICM

TOWED

(14 MINS)

SHOOT THEN SCOOT

33 MINS

63%

TAKE COVER

45 MINS

22%

MHO A-2

D-30

SO VOLLEYS

SCOOT THEN SHOOT

22 MINS

WITH HE

TOWED

(14 MINS)

SHOOT THEN SCOOT

18 MINS

22%

TAKE COVER

42 MINS

1S2

M110 A-2

18 VOLLEYS

SCOOT THEN SHOOT

41 MINS

14%

WITH HE

(30 MINS)

SHOOT THEN SCOOT

53 MINS

54%

TAKE COVER

52 MINS

Motes: *The U.S. 8" weapons fire at an average rate of one volley per
three minutes in these suppression missions. The Soviet
152 nun weapons fire at the more typical Soviet average rate
of one volley per minute. Soviets use six-gun batteries, the
M110 is a four-gun battery.

In order to make the four cases shown in this table comparable,
all victim missions consist of firing the same weight (6500 kg)
of projectiles. Times shown in parenthesis would be required to
execute this mission if the victims were not being suppressed.

Inspection of these results indicates that it is always advan

tageous for tho Soviet units to interrupt thoir fire missions and
relocate when th»y receive incoming. For this reason, this tactic
has been attributed to Soviet artillery units in the combat analyses
referred to in this paper. In this view, suppression really amounts
to time lost due to forced relocation. The time required for Soviet
batteries to reestablish a position and commence firing is minimal due
to the availability of accurate land navigation systems in all of their
batteries.

The trade-off between tactics is less clear for the U.S. 8" M110
A-2 weapons which are self-propelled but not armored. So long as the
Soviet forces use HE ammunition in counterbattery fire and U.S. materiel
is precious, the most advantageous tactic is to have the crews take
cover until suppression lifts. If the M-110 series were modified to
be as survivable as the 1S5 mm M-109 and the crew members given
equivalent protection, it could shoot-then-scoot in 36 minutes with
18% attrition or scoot-then-shoot in 38 minutes with 5% attrition
under the conditions of the example.

Two observations based on the above analysis and examples:

e As DPICM becomes generally available and single volley kill
probabilities of about 20% are achievable against towed gun
crews and about 2% against SP weapons, the primary suppressive
effect on artillery batteries will be forced movement.

• As the best evasive tactic for the victim appears to be to
leave the battery position quickly, much ammunition should
not be spent in protracted suppression attempts unless there
is information to the effect that the position has not been
vacated.

• *n« w

S.O SUPPRESSIVE EFFECTS IN COMBAT MODELING OF ALL-SP FORCES

The examples of the last section show pretty clearly that in a one-
pn-one situation there is considerable advantage of vacating a position

when a battery begins to take serious incoming fire. This is particularly
so for SP weapons, both because they are larger than towed pieces and
hence more vulnerable to DPICM and because, being agile, it is easier for
them to displace.

It is these forced moves of weapons which interfere with artillery
productivity and in effect cause SP artillery to be suppressed. The mag¬
nitude of the effect and its impact on overall combat cannot be judged on the

basis of one-on-one analysis; it is necessary to use more comprehensive
analyses which represent the interactions of many military units and
different types of equipment, and this of course requires computer simulation.
One computer program useful in this respect is the Stochastic Artillery
Combat Model (SCAM) which simulates the field artillery counterfire duel
of a i'.S. division with resolution to the level of individual weupons,
crews, target acquisition, and C3 assets. SCAM is two-sided and sym¬
metrical with respect to the degree of detail and the interactive processes
modeled for each side. Monte Carlo techniques are employed to reduce the
performance statistics of the various battlefield systems to discrete
events which the model tabulates. Systems are represented in terms of
their technical performance characteristics, and a large number of decision
parameters are available to represent tactical and doctrinal choices such as
response to incoming fire, shoot -and-scoot procedures, etc. Small dis¬
placements which do not affect battlefield geometry are used to represent

forced evacuation of firing positions, and the time during which batteries
are vulnerable while relocating as well as time to reestablish a fire
position can be selected. Statistics pertaining to ammunition expendi-
ture, attrition, and suppression, as well as many other factors are accumulated.
Suppression is treated in terms of actual weapons effects and logical decisions
are based on maximizing survivability or productivity depending on mission
urgency at the time. The demand for target servicing indirect fire (TSIF)
is an exogenous variable obtained from war gaming or general combat models,
but the amount of TSIF delivered depends on weapon and munition availability,
target list length, fire control time, mission priority, and numerous con¬
ditionals of system interaction. All in all, a reasonably accurate picture
of artillery activities and effects is portrayed by this model. Numerous
combat simulations have been run with SCAM to address various points, but
most relevant here are some results which bear on the understanding of
suppression.

As the primary object of counterfire is to reduce the amount of TSIF
which the enemy artillery can supply, it is of interest to examine the
factors which limit this. SCAM has been used to simulate the artillery
battle in the SCORES European scenario which depicts a Soviet attack in
the Fulda area. Principally, we have studied a 1986 technology scenario
in which all Soviet cannon artillery units are represented as having self-
propelled armored weapons. The first limit on the Soviet TSIF rate is
imposed by the number of weapons, their technically achievable rates of
fire, the Soviet doctrine on destructive effect per mission, and the C2
time required per mission. Consideration of these factors loads to an

estimate of 55,000 rounds per hour as an upper limit on the amount of
TSIF which could be provided by the Soviets. Ammunition resupply capa¬
bilities are estimated to be more constraining and would apparently limit Soviet
TSIF to about 24,000 rounds per hour.

The remaining factors which limit TSIF depend on the scenario under
consideration, but the situations investigated with SCAM appear to be both
reasonable and representative. From analysis of l.egal Mix V data we have
established a rate of calls for TSIF based on considerations of turget
presentation rate and acquisition capabilities. If there were no U.S.
counterfire, the Soviets would respond to these calls by providing some
11,000 rounds per hour of TSIF, a figure which is well within their technical
and logistic capabilities, indicating a large capacity for absorbing
punishment.

Assuming the availability of FIREFINDER, TACFIRF, GSRS, and enough
DPICM, the effects of U.S. counterfire efforts in this scenario can be
assesses . We find that the counterfire campaign is able to reduce the
Soviet TSIF rate, by more than half, to 5,200 rounds per hour, while ap¬
proximately forty Soviet weapons per hour are being killed. The result
is somewhat surprising in view of the apparent over capacity of the Soviet
system. Why is the Soviet force so Inhibited? It should, in principle,
be able to fire many more rounds if called on to do so.

In an attempt to understand the situation more fully, :i special SCAM
run was made which explores an artificial situation: The logic which
forces victim battery movement in order to maximice survivability and
productivity in the face of highly lethal incoming volleys was retained,
but no kills were permitted. Thus, the pure suppressive effect was

separated from the pure attritive effect, with the enlightening result
that the Soviet TSIF rate turned out to be 6,600 rounds per hour. Let

us recapitulate these figures:

- With no counterfire, Soviets fired 11,000 TSIF rounds per hour.

- With counterfire without attrition, Soviets fired 6,600 TSIF rounds per hour.

- With attritive counterfire, Soviets fired 5,200 TSIF rounds per hour.

Thus, of the 5,800 rounds per hour reduction due to counterfire, 4,400
rounds per hour or 75% is ascribable to the (non-lethal) suppressive effect.

There is no doubt that forced movement is a very real and important
contributor to fire support suppression. It must be emphasized, however,
that the analysis is indeed scenario dependent, and it would be very mis¬
leading to take the results of the example just cited and use them out of

context. In most SCAM simulations, we have required the Soviet cannon
artillery to fire some 360 rounds of HE or 120 rounds of ICM per TSIF
mission. These figures seem to be in accord with what the Soviets say
they will fire to achieve their desired level of damage; such a doctrine
does lead to long missions, however, and long missions get interrupted
by efficient counterfire. Looking more deeply into the example above, we
find that while in all cases the Soviets were responding to well over
ninety per cent of their calls for TSIF, the average number of rounds per
mission is only half of that desired when they are faced with counterfire.

This, of course, is because their missions are interrupted by counterfire.

Thus, if the counterfire system is not very rapid and responsive it will
not be effective. Similarly, high rate of fire weapons such as rocket
launchers which fire once and move out immediately are almost impossible

to suppress by returning fire on their launching positions. Other SCAM
runs which model the Soviets as firing the same number of rounds per
mission as would be indicated by U.S. doctrine, show that it is much
more difficult to conduct effective counterfire in this circumstance
because very few of their missions get interrupted. These results suggest
that it may be possible to devise some optimal doctrines and technologies
which minimize the effects of enemy suppressive efforts. Shoot -and-scoot
tactics using ultra high rate of fire weapons appear very promising and
offer an important difficult new problem for opposing target acquisition
and counterfiro weapon systems.

Acknowledgments

Dr. Mat Oldham suggested the basic approach used here to describe the
suppression of towed artillery crews. Dr. Neal Plotkin originally
proposed the increased risk parameter as a way of approaching the
question of how long such crews should stay in a protected, non¬
productive state. Mr. Richard Carpenter wrote the SCAM program and
has been instrumental in its application to combat modeling problems.
These and other colleagues at MITRE have contributed numc-ous in¬
sights in the course of many discussions.

O i

APPENDIX F

Toward a Theory of Suppression
By

HERO Staff (Historical Evaluation and Research
Organization, A Subsidiary of
T,N, Dupuy Associates)

TOWARD A THEORY OF SUPPRESSION

A HERO Staff Paper

Any soldier who has been under hostilr which cnn cau-g suppression, the action

artillery fire or nir bombardment »3 famil- which most nhvimifly and clearly results in

iar with the experience of suppression, supprnsn Ion In tlim of riirertin.i lethal fire-

whether he ha* ever heard the term or not, power at nn enemy.

The eupprcssion he know may have boon brief

— lasting only while he heard the whine of suppression, Dispersion,

Incoming shells, or the detonations of those DliirjyuTpn

sheila or of aerial bombs. Or if. may have

'lasted until all hostile aircraft, were out tn search i mi for m.ml festal 'inns of the

of sight. Or--l f the bombardment wan par- impact of suppression, we may look first at I

ticularly intense or prolonged--! lie teclinq I ho increasing dispersion of military forces

of terror and shock that even the bravest in combat an firepower weapons have become

men feels under such circumstances may have more ,and more lethal. There in no doubt

lasted for some time after the last explo- that this relationship is real. The graph

sion faded from his ears. However long it. in Figure 1 shown visually the relationship V

lasted, his combat performnner--onorgy , between increasing lethality of weapons and

strength, initiative), skill, mobility — wan ntaudily greater dispersion. As a result

degraded for that period of t,.ime. of this ineteaning dispersion, there has

In hla article "The Shock Impact of been a general tied inn in combat casual Men

Combined Arms Forces in World War tl Amph I - nvt>> the enurse of modern history since the

bious GperationB," published in t in.' most I ntrodgei ion ot gunpowder weapons in the thth

recent issue of HISTORY, NUMBERS , AND WAR, nnd 16th centuries, although this decline has

the late S.L.A. Marshall mentioned n mimbur been neither steady nor consistent,

of instances of suppression-- ind ud 1 nn some tt is likely that the greatly Increased

in which the supprosalve effect of gunfire dispersion that has occurred reflects not

end bombsrdmant was very successful and only a response to the direct effects of

some in which it was loss so. The sergeant enhanced lethality (that is, the vulncra-

whosa description of the effect of hostile bilit.y of. closely massed troops to such

Omaha Beach fire on hiB physical strength weapons nn Innli-explonivo shells), but re-

wes quoted by Marshall--t.he man said ho had fleets also the effects of suppression,

barely been able to lift a machine-gun part: Troops experiencing the suppress jvp physical

ha usually ran with--was obviously suppressed and psychological effects of fin? nnd bom-

by the hostile fire, and the suppression ef- Hard ment. are inevitably inhibited nr de¬
fects lingered. gradod i n per f fuming such important tactical

Thus, while It may not be easy for sol- processes as manuevcrlng, but lean so when

diers who have been suppressed by enemy fi.ro t.hcy are deployed in open order rather than

end bombard non t to define the term in mass. Thus dispersion is clearly a re¬

sist!, they well know what it means, rt in ■ active manifestation or the effectiveness
en undeniable, and very important, phenome- of suppress i on .

non Of combat. other probable evidence of the signi-

For the purpnnos of thin essay, rind finance of d l :t| ■<» r .m i on han been ■ !u> j uerenn

subject to possible revision an ,1 result of i ng effort to provide additional prelection

further study and analysis, siipprer.n ion can to troops, through field fort t I M • a t ions, or
be defined as followat armor, or mobility, or various combinations

of 1 hone prnl nl i ve me. inures, I'lolncted

Suppression is the degradni ion troops not only arc more likely to survive

Of hostile opera t. Iona I rnp.ihtli- fire and bombardment: they .» I ■ . feel safer,

ties through the employment of and t luc. inevitably. I inn what we know of

militaiy action which has psyeh- the phy- ai etrcct'i of ten, they p.-i form

Oloqlcai or physical effect-; im- better.

pairing the combat performance Still other, and mere direct, manifes-

of enemy force* and individuals rations of the siipprivisinn effect are sgrh

who have not themsolvep been combat phenomena an t lie inability of troops

rendered casualties. to advance ngninnl effective, nuncr! defen¬

sive firepower, and the silencing of arttl-
Tliere is obviously on unmistakable, lery formations by rngntorbnt t cry tite,

but so far not readily definable, relation- These failures are often out of proper t: ion

ship between casualties created by firepower to actual casualties taken. The rtrepower
and the suppressive effect of that firepower that stops the attack nr silence-, (lie hos-

nn i- hose who either escape or evade the di- tile artillery may or may not inti let sub-

rectly lethal effects of firepower. WhiLc stnntlnl casual t i it in the target formations,

it Is pooalble to visualize oilier act ions But even if the , -n a 1 ' Ins are not ■■ i gnl f leant ,

(he firepower hae hren effective, Iw-i-nunr
It hqs rendered the npp?)ivnt 'i .11 I If'm-

IKirarlly Ineffective.

Although ncriOtlB cons I der.it Inn linn horn,
and la being, given to i he <|uor.tion of rc-
proaentinq suppression in modern model?! of
combat., there has been no known effort to
analyze suppression or its relationship to
weapons lethality— either in connection with,
or independently from, casualties- for the
purpoi e of determining the morphology of
suppression, or to meanure its effects.
However, HERO has perfofmed two studies that
could have considerable relevance to auch
analysis. Ona of these--"Histor icel Trends
Related to Weapons Lethality"--wns performed
for the U.S. Army Combat Devel opmen ts Com¬
mend in 1965. The other--"t)isruption in
Combat"— wae dona for the U.S, Air Force,
Studies and Analytic, Oenernl Purposes and
Airlift studiea, in 1970.

rurfeharmora, in the development of the
Quantified Judgment Method of Analysla of
Historical combat Data (QJMA) , ,and its com-
ponant Quantified Judgment Model (QJM) , HERO
hae found It poeaible to fjunntify the dis¬
ruptive effect of surprise, and also to
relate normalised casualty-inf lici ing capa-
bilitias of military forces to combat of-
feetlveneas. Since there is an obvious re¬
lationship-even though not yot a readily
definable one— between suppreMuloii, disrup¬
tion, and caaualty Infliction, thin past
work offers considarabie basis for confi¬
dence that comparable quantification is pos¬
sible for the effacta of suppression.

KERO has recently completed research
for the Department or thu Army on nrlillery
rates of fire In recent wars, fn the course
of this work and in rasearch for other
studies HERO has repeatedly found referenced
to the suppressive effect of artillery fire
For instance, in n classic British Operation*
Reeeerch report of World War If we find the
following words i

"There la the question of numbers
of shells as opposed to sheer weiqht
--the aqc old argument, in another
form of field verson medium artil¬
lery. There arc a lot of jobs
where the heavier siiolls are es¬
sential, either because of their
greater range or greater penetra¬
tive and explosive powers, nut
where lightur stuff can reach,
end la capable of hurting the
enemy, the evidence of these two
reports seams to be that the thing
that counts most of all is the
number of bangs. Clearly om- 100
pound ahell is better than one 25
pounder one. It le on the other
hand very questionable ,whrt her it
is four times better."'

It is perhaps slno slqnt r leant Mint in
its analysis of current Soviet artillery
practices, HERO has noted a strovi explicit.

emphasis on achieving "neutralization." The
■iriillcry fire methods of Soviet and some
r j l Ikt armies combine periods of intense fire
w i Hi intermissions during which there is con
t.lnuing fire at a much lower rate. This
method implicitly recognizes that the ef¬
fect of suppression is achieved by Rome com¬
bination of maaaive shock action and uncer¬
tainty over a longer duration. It is clear
from soviet literature, furthermore, that
the Soviots are attempting to quantify sup¬
pression; a more thorough study of soviet
military literature may give some hint as
to their findings.

Tactical nuclear and chemical weapons
would seem to be ideally suited for the
sehiovement of suppression substantislly in
excess of the direct casualties they may in¬
flict., By properly mixing the delivery of
maaaive strikes and randomly timed fires it
would appear to bo possible to build on the
already extreme psychological effacta these
weapons will produce.

On. the other hand It is undoubtedly
possible through proper training and indoc¬
trination to reduce the effecta of suppres¬
sion hy increasing the troops 1 ability to
function under stress. There are many his¬
torical examples which show that a given
amount of firepower had a more devastating
effect on one force than on another. This
of course is the reason armies attempt to
make their training sa raaliatie as possible
Yrt no one 'has integrated numerical factors
representing the ability of a force to with¬
stand suppressive fire into an expression
roprosonting the disruptive effocth cf such
fire, in order to develop a single modal to
explain and evaluate suppression.

A re There Lawa of Combat?

The demonstrated lnterrelationnhip of
‘firepower, mobility, and diapeision, and
the potential relationship betweon the sup¬
pressive effecta and the casualties of fire¬
power, sugqest the possibility of a theoreti¬
cal interrelationship of basic combat mea¬
surement unit* similar to those that are
found in mechanics, hydraulic theory, and
electrical theory. In electrical theory,
for instance, there are predictable, measur¬
able relationahipr Involving ohma of resis¬
tance, volts of electromotive force, amperes
of current, coulombs of charge, henrya of
inductance, farads of capacitance, watts of
power, and joules of energy.

It is possible that some day someone
may determine that there are lawa governing
combat that ara comparable to Newton’s Laws,
or to Ohm’s Law, and so forth. This possi¬
bility todsy seems to ds far beyond "the
state of the art" of military operations re¬
search or historical analysis of historical
data, but result* of HF.RO research suggest
that historical combat data will permit em¬
pirical exploration of the general validity
(or invalidity) of the following hypothesis;

Interrelationship* amonq comb, it
•phenomena and processes can bo As¬
certained in terms of throe "fire¬
power laws of combat”;

1. Combat power is the product of
firepower and all discernible en¬
vironmental and operational vnri-
ablea of combat;

2. There is a dynamic relationship
among firepower, mobility, and
dispersions

, j . Firepower cels be defined Its
terms of combat effectiveness,
casusleies, and suppression.

The first two of these "firepower laws
of combat" have been oubetnatial 1 y demon¬
strated by HERO'S QJM and other theoretical
work, although the exact mathematical nature
of the relationships cannot yet. be stated.'
The third "law" is a highly tentative hypo¬
thesis, which may be proven, or modified, in
the process of historical research and anal¬
ysis. If this hypothesis can be only par¬
tially or tentatively substantiated, however,
it provides e means for bettar asar-sing the
nature of suppression, and for determining
means to msasuro it.

Are There Msa suras of
Supprbtalva' Effectiveness?

Another area of HERO'S paHt research,
related to the development of the QJMA, also
seems relevant to the measurement of sup¬
pressive effects. HERO has demonstrated -
rather conclueively we believc--that the
outcome of a past combat engagement--who
won and who lost, and how decinively«-can
be stated t i meaningful quantitative terms
by applying three measures of effectiveness
to the performance of the opposing forces i

1. Relative mission accomplishment,
or the extent to'wKlcfi the ""To rcc* accompli shed
ite eeeigned or perceived mission during the
engagement; thin must be determined from on
analysis of records by an objective h'.stor-
ien--prefsrably by two or more historians
since this assessment cannot avoid being
subjective, no matter how objective the his¬
torians;

2. 8patlal ef foctivenpas, or the dem¬
onstrated «ETTTEy-oTTTis~7orce to qalr or
hold ground during the battle; this can be
calculated by an empirically derived formula
that considers the opposing force strengths,
the quantified posture factors for each side,
• 'if: littlefiold depth of the opposing sides,
and the distance gained (or lost) during t.he
course of the engagement;

3. Caaunlty effectiveness, in which
the personnel lossee of the two sides .ire
compared in another empirically derived

formula, whii-h al-so <r>nsidorD the starting
strength;' or Imi h sides.

The values "i i in* so measures of effec¬
tiveness, Mnpit.il, ly nr in combination, are
obviously iffnnii ii i.y g ) ) or most of the
many variables of combat that influence com?
bat outcomes. Not , -minting suppression as a
combat vnrlab), (which it prohably is), HERO
has identified some 7.1 different kinds of
combat variables which are believed to in¬
fluence battlefield results." tf it can be
found that the values of these measures of
ef feci I venenn viry to any degree in rela¬
tionship to the weight or vojume of suppres¬
sive firepower delivered hy the oi'poii 1 ng
Hide--or delivered hy one's own side--then
it may be possible to find ways to measure
the extent to which suppressive firepnwer--
rather than norma t or abnormal combinations
ot the other ,1 variables of cornua t --has
boon effective in a particular engagement.

Some Quest. tonii for Researchers

The discussion up to this point, suggests
that there may be at. loaRt. two different ways
of asnnsMing or measuring suppression i (1)
an an element or three interrelated firepower
laws of combat, uinl (?) by usn of throe com¬
bs I outcome mesniires of of feet i venous . The
two approaches ir>> not mutually exclusive,
a 1 though II in obvious that either can be
attempted Without the other. Ret tor, how¬
ever, to try hoi h — ^ .separately and (if pos¬
sible) together. The extent to which those
approaches can m should |>e related 'to each
other should l.ei-onie evident f a I r 1 y ' o,t r 1 y in
tile researrh pioee:.;i.

Whatever the approach, some of th*
questions that will need to bo answered ara
already apparent. Three of those appear to
hr-- basic:

I. How is suppression measured? la
it a function of weight of fire (ie tons of
steel and high explosive), or of. volume of
fire (in number of rounds), ot of some com¬
bination of them?

*' What in the process of suppress Ion?
ts thorn a relationship between r -i uu.t 1 M ert
and suppression,’

1. What are the determinants of sup¬
pression?

In this process it may also be possible
to obtain answers in a me err of other
questions, .surh as:

1. Mow dors the amount, of suppress 1 vr
(Ire relate tn asnpssmontfl of total enemy

| mwer ?

2. Ilov does the spacing of .suppres¬
sive fire relate to willingness to move
forces and to the expectation of casualties?

fifl

awiiMiiMiiimttikiiiiaiaat

I?-

. - . . . \ . " -TOH'.WiMllg'iHiU ■

- - y - ;

5. How does , parcel ved effectiveness of
suppression relate to chanqes In attack plans?

4. To what degree does suppression ef¬
fectiveness relate to common! cat Ions disrup¬
tion and to what degree does such disruption

create a poaitive feedback loop?

5. How do amount and timing of suppies-
■ive fire relate to the individual and com¬
mand eatimates of overall power of the de¬
fender?

, 6, How do volume and density of sup¬

pressive firepower relate to estimation of
one* a own casualties?

Possibly the Soviet* have discovered
some way of confidently assessing the quan¬
titative valuo of suppression. It is clear,
however, that, in the West there arc today
many questions and almost no answers about
thia important phenomanon of combat, we
bWliave the above h-m il ' Hnn-f suggests
thAt it wa can determine which questions
are critical, and explore those further, we
may finally • able not only to understand
but evan to measure suppression.

NOTES

).. Number > Operational Rem-arch Soction roport to
Hie army Connell, "n|.»rn linn/il Research in H.W.
l-iiiinpe “ (UinrloM, n.d. I , I*. ISR.

y. see,, for inntnnee, william C. Stnwart, "Intgfsc-
lim, of Firepower, Mobility. arid Dispersion," Mlilm
Id-vti'w, Mareh lOMii and T.N. Dupuy add Janice
n. Inin, "The t-awi governing Combat," Nation*! De-
fnnftt't April 197r>.

1, ft sthould ho m*rip nlnar At thia point that thaaa
,ttn rnmMfet vat i abl f>H as soon by military hlutoriinif
twit hy WA^homni.iciflnnj linn lint of 11 intrludaa iuch
li.tcil weapon**, and weapon^ charactori*tic«»

boc.iunct khoy vary from one nn<iA9®"*ht anothari
thuftf* are obviounly not mathematical variables*

DISPERSION: SQfOMB METERS PER

WEAPONS EFFECTIVENESS AND SUPPRESSIVE FIRE

AOM xm
Fore La«, VA
October 1974

Mr. George M. Givi den
US Army Research Institute

PURPOSE:

The purpose of this presentation Is four fold:

First, to summarize previous research In the area of suppressive
fire as a component of weapons effectiveness.

Second, to discuss several attempts to develop valid models which
would define the relationship between weapons characteristics and ef¬
fectiveness In suppression.

Third, to Identify some of the contributions of suppressive fire
studies to weapon systems design and procurement decisions.

Fourth, to clarify the primary Issues relating to proposed re¬
search In the suppressive fire area.

The primary emphasis will be on small arms weapons systems. The phe¬
nomena of suppression Is complex; all too often those who would perform
research In this area have committed the error of oversimplification,
falling to realize that suppression Is a function of literally hun¬
dreds of different variables, of which weapons characteristics represent
only a small number.

The effectiveness of any weapons systems Is a function of Its performance
In each of the roles that It will be expected to fulfill. The primary
function of weapons Is to decrease the effectiveness of the eneiw. This
may be done by eliminating these enemy forces or by preventing them In
other wavs from accomplishing their objectives. Weapons may be ef¬
fective by physically Incapacitating the enemy or by psychologically
reducing his effectiveness. Any research program to Improve weapons
effectiveness must, therefore, concern Itself with first Identifying a
set of measures, of effectiveness, and second, with Identifying object¬
ive relationships between these effectiveness measures and weapons •
characteristics.

Previous studies have teen consistent In Identifying five major Inter¬
dependent measures of effectiveness for most weapons systems: ,

Hit capability

Suppression capability

Lethality

Reliability

Sustainability

All are time related, and each Is a function of the others. Thus, the
weapon with a high single round hit probability may not have as great a

503

hit capability In combat as a less accurate weapon which can put out a
much greater volume of fire within the same time span.

In this respect, Combat Developments Coimand Experimentation Command
(USACDEC) tests showed that soldiers equipped with 7.62mm M14 rifles
consistently hit more long range targets per round of anmunltion fired
than did Ml 6 flrers. However, Ml 6 f i rers ( firing's . 56 rrcn rounds that
weighed only half as much) scored significantly more hits at all ranges
per pound of ammunition fired. M16 nits were also secured more quickly
than Ml 'f Fits, which means that M16 flrers would have been subjected to
a shortened duration of return fire from the enemy.

The Ml 6 flrers were also able to sustain their fire effects for a longer
period of time due to the lightness of the weapon and ammunition which
permitted more rounds of ammunition to be carried. Within the basic
weapon system weight of 17 pounds prescribed for the rifleman, the Ml 4
soldier carries only 100 rounds as opposed to 300 for the soldier armed
with the Ml (5. If time Intervals of fire were equated, and rates of fire
were identical, the Ml 6 flrers would have been able to sustain their
effects for three times as long as the Ml 4 rifleman.

On the other hand, a weapon with an extremely high single rounci hit
probability may be relatively Ineffective because of low lethality or
because Its reliability Is so low that It Is unable to flra many
rounds because of malfunctions, In like manner, the suppressive effects
that a weapon produces may be diminished by high malfunction rates or by
Inability to transport the quantities of ammunition necessary for sus¬
taining fire. The suppressive value of small arms weapons systems Is
also diminished when the weapon's projectiles are not perceived as being
very lethal; and when projectiles are not perceived as being threat¬
ening, suppression will not be effected.

Mobility of weapons Is a component of sustainability in that the amount
of ammunition a soldier can carry Is diminished as the v/eight of the
weapon Increases. As sustainability of a weapon is increased through
Increasing the ammunition load, mobility is correspondingly made more
difficult and decreased.

THE NATURE OF SMALL ARMS SUPPRESSION RESEARCH

Although all of these five measures of effectiveness are components'of an
integrated system of effectiveness, each may be considered and examined as
a subsystem. In this yespect, hit probabilities, lethality, reliability
and sustainability have been the subject of far more detailed research
than suppression. This Is attributed to the fact that each of the
first four is more easily studied quantitatively from the point of
view of the physical sciences.

For example, rifle hit probabilities may be physically measured in
terms of hits on targets as a function of specific measurable ranges
and number of rounds fired, while reliability Is basically a matter of
compiling numbers, typos and causes of malfunctions over a period of
the weapon life cycle. Sustainability of a weapon system may be studied
as a function of rates of fire, basic loads of ammunition, logistics

■ li"l ill'ill'11 itil ^miii

504

and similar numerical factors. Lethality Is a more complex measure
but extensive data hove been made available from gelatin block
experiments, penetration studies, animal studies, and studies of
human wounds In combat to Include extensive medically based class¬
ification schema.

On the other hand, suppression deals with numerous psychological
factors. There is, of course, "permanent suppression" from physical
factors — the soldier who Is severely wounded or killed becomes
"permanently suppressed" -- but studies in this area fall under the
"nit capability" and "lethality" categories previously mentioned.
Psychological suppression from small arms fire Is a more complex
phenomenon. Unlike hit capability and other effectiveness measures,
suppression or its causes cannot be measured directly In most cases.
Since phenomena within the human mind are of concern, casualty must
sometimes be Inferred or indirectly established.

Furthermore, It Is not possible to study suppression primarily as a
system of discrete numbers. In researching hit capability (to Include
hit probabilities), a target Is either hit or It Is not. When con¬
sidering lethality, the reaction of a gelatin block to the penetration
of the bullet may be recorded and measured by high speed photography.
But such finite physical measurements are usually not possible when
one examines suppression.

A period of slightly reduced effectiveness which lasts only several
seconds may constitute suppression In one instance while In another
case suppression may consist of an Imnobllizlng terror and shock that
results In a prolonged total Incapacitation requiring psychiatric
treatment. Furthermore, the reaction In the same soldier to the same
stimuli and cues may be vastly different from one time to the next.
Suppression Is also Influenced by a much greater variety of extraneous
factors than the other measures of small arms effectiveness. Training,
leadership, morale - even religious beliefs - are only a few of the
many factors that determine the degree of suppression that may be
effected on any one indlvlducl at any' given time. Suppression,
therefore, become* the most complex component of weapon systems combat
effectiveness studies.

DEFINITION OF SUPPRESSION

Host previous suppression research has been concerned only with
suppression by small ai?ns fl.re. On the other hand, small arms fire
Is usually only one of many types of weapons fire contributing to
suppression at any given time. Even In the final stages of an assault
when only small arms are being used, the suppression that occurs may
be, In reality, only a continuation of the suppression effects that
occurred as a result of heavy preparatory tank, mortar, and/or
artillery fire. Although there are many and varied definitions,
suppression Is operationally defined here as:

"A state of relative ineffectiveness or incapacitation
of the Individual soldier which is a function of
psychological factors, and which Is either Initiated
or maintained by a perceived threat from weapons fire."

505

Within a psychological framework and In tlie language of the psychologist*
suppression Is defined as:

"The resolution of an approach-avoidance conflict In

an Individual by taking the avoidance response."

DIMENSIONS OF SUPPRESSION

Previous research studies Indicate that there are five primary
dimensions of suppression and that It Is Important to understand
these dimensions prior to conducting any Investigation of suppression
for the weapons characteristics most desirable In one case may not be
applicable In another. These five dimensions are:

• Reasoned (Rational) Suppression versus Unreasoned (Irrational)

Suppression.

In reasoned suppression the soldier rationally analyzes the
situation and mentally calculates the probabilities for mission
success and survival. The soldier who keeps his head down and cooly
waits until the enemy has exhausted much of his ammunition before
resuming the assault has had his effectiveness temporarily reduced
and, therefore, has been suppressed. This constitutes reasoned
suppression. On the other hand, the soldier who reacts out of panic
or psychological fear without consciously thinking or considering the
real nature of the threat or long term effects Is reacting without
reason, which constitutes unreasoned (Irrational) suppression.

• Area Suppression versus Point Suppression.

The suppression resulting from mortar fire or from the classic
distribution of machine gun fire between two reference points is an
example of area suppression. The soldier who has been suppressed
as an Individual by sniper fire or by an enemy machinegun specifically
aimed at his location has been Incapacitated by point suppression. The
weapon which Is best for area suppression may be relatively unsatis¬
factory In a point suppression role.

• Defensive Suppression versus Offensive Suppression.

Some of the weapons characteristics which make the greatest
contributions to effectiveness of suppression In offensive situations
may be different from those most desired in the average defensive
engagement. One study, for example, indicates that the infantry
weapon with the greatest suppressive effect against assaulting enemy
troops Is the machinegun, whereas the weapon providing the greatest
suppression against emplaced defending enemy troops is the mortar.

The recoilless rifle 1i: perceived as more effective than the auto¬
matic rifle aaalnst defending troops whereas the reverse Is true
against assaulting troops.

• Lethal Suppression versus Denial Suppression.

Suppressive fires may be used against an area or positions that
the enemy is known to occupy. In these instances, the objective is
to neutralize the enemy by preventing him from moving or using his

S06

weapons or by killing lifin If ho attempts to. This is known as lethal
suppression, whether the "suppression" occurs by physically killing
and disabling the enemy, or whether it occurs as a result of a
psychological fear which causes the enemy to remain immobile and not
use his weapons. Denial suppression is used against areas unoccupied
by the enemy and is used to deny them access to that area or position.
Continuous bursts of machinegun fire fired down a stretch of road or
across the entrance to a bridge are examples of denial suppression.

The same psychological factors that prevent a soldier from sticking
his head out of his foxhole to fire his weapon also keep him from
venturing up the slope of a hill through Interlocking machinegun
fires or exploding grenades.

e Direct Fire Suppression versus Indirect Fire Suppression.

This dimension, of course, is a classic one. In the case of
small arms, grenade launchers and hand grenades are considered to be
the only effective weapons for use in the Indirect role while rifles,
automatic rifles, machineguns and grenade launchers may all be used
for direct fire.

DEGREES OF SUPPRESSION

As already discussed briefly, suppression is a state which may last
for only a few seconds or It may "permanently" incapacitate a soldier
just as effectively as a bullet, to the extent that the soldier must
be evacuated for psychiatric care. S. L. A. Marshall's description
of suppressed American soldiers on ftnaha Beach on the afternoon of
D-Day, June 6, 1944, is an excellent example of the latter:

"They lay there motionless and staring into space. They were
so thoroughly shocked that they had no consciousness of what
went on. Many had forgotten they had firearms to use. Others
who had lost their firearms didn't seem to know that there were
weapons lying all around them. Some could not hold a weapon
after it was forced Into their hands. . .Their nerves were
spent and nothing could be done about them."

At the other end of the continuum would be a hypothetical soldier who
Is not subject to suppression, who does not duck or in any way adjust
his actions as a result of being suddenly brought under fire, and,'
who, because of his foolishness, dies! The majority of historical
Instances of suppression lie somewhere between these two extremes.

Many researchers in the past, particularly those who have not
experienced Infantry combat or who have based their studies .solely
on after-action Interviews, have been unsuccessful because they did
not understand the desired objective of suppressive fire or its full
psychological implications. The objective of suppressive fires is
not. just to neutralize or Incapacitate the enemy during the time he
Ts being subjected to suppressive fire. Effective suppressive fire
(of the "Lethal Suppression" type) Is such that the enemy remains
incapacitated for a period of time after the fires are lifted. This
period of psychological shock should Ideally be of sufficient duration

50?

to permit friendly forces to fully exploit their advantage, c.g., novo
onto the enemy position in an assault arid capture or kill the stunned
enemy in their emplacements without receiving return fire. The length
of this post-suppressive fire incapacitation will vary from a few
seconds to minutes to hours depending upon many factors, some of which
will be discussed later.

It is extremely difficult to collect valid data on these post-suppres-
Sive fire investigations through the use of interviews and question¬
naire techniques. In most cases there is no stigma attached to having
been pinned down or suppressed in a fire fight. In fact, every infantry¬
man who has served In combat for any length cf time has been "suppres¬
sed" many times. But for a soldier to admit post-suppressive fire
Incapacitation (that he did not fire his weapon or that he remained
temporarily In a state of shock In the bottom of his foxhole after
enemy fire was lifted) is something entirely different, for the label
and social stigma of cowardice Is attached to such conduct. The most
feasible approaches for collecting Information in this area are
interviews where the responder is asked to describe the conduct and
actions of his fellow unit members, or when anonymous questionnaires
are used In a group setting.

Point Suppressive Fire may also be quite effective. Military history
is replete with examples of lone snipers who were able to quite
effectively suppress or delay the advance of entire units.

The degree of suppression Inflicted upon a unit may be measured in
two categories. The first Involves the degree of incapacitation
suffered by individuals, whereas the second involves the total number
of personnel affected within the unit. Theoretically , the sane loss
of unit effectiveness might result from all unit members being slightly
incapacitated, as from a fraction of the members being severely affected.

Suppression, therefore, occurs on a continuum ranging from Incapacita¬
tion requiring evacuation to no Incapacitation at all. It may seriously
affect only several members of a unit at any given tine, while at other
times all members of the unit may be pinned down simultaneously.

FACTORS AFFECTING SUPPRESSION

Although most research projects are primarily concerned with deter-*1
mining objective relationships between weapon systems fire character¬
istics and effectiveness in suppressive fire, we cannot Ignore all
of the other factors that contribute to suppression in any given
situation. We have already discussed the five primary dimensions of
suppression and emphasized that those factors which most influence
suppression in one situation may have relatively little effect in
another.

Litton's Defense Sciences Lai oratories , during the course of extensive
work in the small anrs area, I 'S obtained and researched more than
1200 documents and combat film-, which initial research indicated were
related to suppression. As a result, much of the background research
work required to effectively initiate a detailed study of suppression

008

has already been accor.pl ishrd, and many of the hypothesized factors
arid weapons characteristics related to suppression have already been
Identified. In addition, literally thousands of combat veterans
(Viet Cong, HVA, Australian, Korean, South Vietnamese and U.S.)
have been interviewed in depth and administered questionnaires
relating to suppression. Field tests have also been conducted.

These research efforts and analyses of previous research reports,
after action reports, combat films, questionnaire results, and other
related material, have identified literally hundreds of factors affect¬
ing suppression. Some make substantial contributions while the effects
of others are negligible in most situations. Many are specific
subsets of a larger more general factor. A sample of some of these
factors that have been Identified ar listed below. Weapons fire
characteristics (often overlapping) • -e listed first, followed by a
short list of other factors which interact to determine the degree of
suppression.

SAMPLE OF WEAPONS FIRE CHARACTERISTICS

Volume of fire per unit time
Cyclic rate per burst
Acoustic signature (volume)

Acoustic tone
Accuracy of fire

Perceived lethality of projectiles

Distance of passing or impacting projectiles from the soldier
Manner of distribution of fire

Coordination of fire with suppressive fire from other types
of weapons
Weapon's basic load
Visual cues

Uniqueness of sound (e.g., ability of enemy to consistently
identify the sound with o p.irtlcwU: weapon)

Actual lethulity of projectiles

Signature cues at tho weapon (e.g., muzzle blast)

Inflight visibility of projectiles (e.g., tracer)

Impact signature (e.g., debris or dust thrown up by Impacting
rounds)

Time to reload
Reliability

SAMPLE OF OTHER FACTORS

Reaction time of target
Previous training
Weather

Availability of routes of withdrawal
Time remaining before rotation
Time of day (night)

Morale

Number of casualties being received by unit while under fire
Proximity to unit leader
Ability to see and be seen by other soldiers
Flrer/target density

These factors represent only a sample of the total possible factors
Influencing the Initiation, maintenance and Post-sunpression fire
effects of suppression.

ATTEMPTS TO MODEL SUPPRESSION

Work by Kinney, Swann, and others at the Naval Weapons Center at China
Lake, California, represents one approach to the modelling of sup-
preslon. Their work has been primarily in the area of fragmentation
weapons used by aircraft to suppress Infantrymen. They have developed
an analytic model for computing suppression effects which uses existing
warhead lethality or P|/ descriptions. The model has been used for
computing quantitative 'estimates of the suppression capability of
the AH- I J helicopter weapon system. However, these quantitative
estimates have no real meaning except in conjunction with comparisons
of similar estimates from other weapons systems. One may also not
be willing to accept some of their definitions or assumptions. Their
model, for example, Is based upon the assumption that the higher the
lethality of a weapon, the longer It will take to recover from sup¬
pression by that weapon. Yet we know of no evidence In the literature
to support this. In fact we hypothesize, for example, that the frequency
and number of low lethality weapons rounds may be such that longer
periods of suppression will result than for fewer rounds of greater
lethality. This study does not consider the weight of rounds, which,
of course, may be interjected later.

The significance of projected size and weight warrants mention at
this time. If we are not careful to consider weight and size we fall
Into the trap of concluding that because the ammunition of weapons
system A Is more suppressive than the ammunition of weapons system B,
then system A must al so be more suppressive than system B! This, of
course, Is not true. For example, the Ml 4 round makes more noise
passing overhead than the MIC. It yields a considerably larger visual
signature upon Impact and under some circumstances is more lethal.
According to all rational criteria it may be considered at least as
suppressive a round as the M16. But, wo have to consider, as mentioned
earlier, that the MIC round weighs only half os ijiuch os the MIA round,
and because of lighter weapon weiqht, 300 Ml 6 rounds can be carried
within the 17 pound 1116 weapons system load •• as opposed to only 100
M14 rounds within the 17 pound Ml 4 basic weapon system load. Further¬
more, most soldiers perceive that if they arc hit in the head with an
M16 bullet they are going to be just as dead as if hit by an Ml 4.

510

It Is obvious then that the MIC , which can put out 3 times os many
rounds [i or uiiit of tin c- per basic load as the* M14, is considerably
more suppressive than the Ml d . In fact, since the hit probabilities
and values (al. expect ranger. of ofigagomont) of ti e two v/capons
were not fat apart, the suppressive superiority of the MIG over the
M 1 4 was one of the primary reasons it was adopted. In like manner,

It makes no sense to say that 40nan grenade launcher are better sup¬
pressive fire weapons than Ml 6 rifles. Quite the contrary, many feel
that 20 Ml 6 rounds spaced out over, say a 1 minute time period, will
have far greater suppressive effect during that minute than one 40mm
grenade which weighs the same as 20 M 1 6 rounds.

The models presented in the China Lake study are applicable only to
weapons with high-explosive fragmenting warheads. Weapons or pro¬
jectiles with non-explosive warheads such as rifles, and weapons with
fuel-air explosive and flame warheads cannot be analyzed with these
models. The study itself, points out that there is still much that
needs to be done. For example, major modeling concepts and Input
parameters have not been validated, and the model does not provide for
anticipatory suppressive behavior which, of course, Is one of the
primary reasons for attempting to effect suppression.

As mentioned earlier, Lltton's Defense Sciences Laboratory conducted
extensive literature surveys, interviews, and questionnaire admin¬
istration and conducted five field experiments In an attempt to
quantify relationships between small arms characteristics and sup¬
pression. The principle findings of this research in which hundreds of
variables were considered were, first, that the major factors producing
suppression were loudness of passing rounds, the proximity and number
of passing rounds and the signatures associated with rounds Impacting.
Within the limits of the distances employed In the study, suppression
was shown to decrease In a linear fashion with Increasing lateral
miss distances of Incoming projectiles. Within the limits of number
of rounds employed In this study, suppression was shown to increase
linearly with Increase In volume of fire. Within the limits of the
projectiles employed, suppression was shown to increase in a linear
fashion with increase in the perceived loudness of passing projectiles.
It was also found, as would be expected, that a combination of both
auditory and visual signatures from near misses was more suppressive
than auditory signature alone. Finally, a set of recommendations for
design considerations to enhance the suppressive capability of small
anus weapons was developed. The study also concluded that a multiple
regression model can be employed to predict the degree to which a
soldier would be suppressed by a given weapon under various circum¬
stances. To predict suppression in combat, the model must Include
such factors as the characteristics of the weapon and situational
variables, and must take Into consideration the experience and
psychological make up of the individual. Perceived dangerousness of
projectiles was an important factor among those .Veading to an Indivi¬
duals' being suppressed. The actual P* value of a round was not shown
to be directly related to Its perceived dangerousness, an assumption
that other studios often make. We cannot discuss details or specific
examples because this information is classified, but we can say that
some of the highest lethality projectiles had the lowest suppression

511

effects, Some of the loudest noise projectiles (AOnm) also have
relatively low lethality while other have high lethality, l.'hore the
inpact of rounds wa s visible, the visual signature had more suppres¬
sive effect than the acoustic signature. The major weapon character¬
istics which should be entered into the model are class of weapon,
projectile caliber, projectile velocity, cyclic rate of fire and the
weapons dispersion. In another Litton study, this time of suppres¬
sive effects of supporting weapons, no quantitative data on suppres¬
sive effects was found. Probably the most important finding of this
research was, and I quote, "The combat suppression phenomenon is too
complex to be amenable to references that rely on laboratory or
experimental findings. . .suppressive behavior is high variaole."

Litton, however, did develop a model (to he used in conjunction with
other research) that requires expected fraction of casualties and a
human factors coefficient as inputs, but recoi.-ncnds again that the void
in quantitative data on suppressive effects should be filled by,
analysis of combat after-action reports that include an orientation
towards suppressive behavior r a the r th_a 1 1 _a ny jJpJVL'lJj: 'r.n 1 1_on , A
method for calculating 5uppressTbTTcVeT"lm(J’ V p'roKiYlffl i Vt'Tc i: odel of
suppression are provided in the Litton report, The model allows for
Monte Carlo runs, expected value determination, parametric studios,
and sensitivity analyses.

As of this time little direct use has been made of the results of
suppression research. The Litton support 'ire node! has been used in
conjunction with the Bonder Independent Unit Action Model in an eval¬
uation of the Bushmaster. At Fort Kenning suuprrssion has boon
incorporated into the Army Small Arms Requirements Study Small Unit
Engagement Model. A Litton model was used here and the Delphi tech¬
nique was used to collect input data. One of tie first real uses of
suppression research data was in the Small Arms Weapons System (or
S.'ilS) study of 1965 and 1966 which resulted in the junking of the Ml 4
rifle and adoption of the M 1 6 . The MIA was a larger caliber rifle
with higher hit probabilities per round, especially at long ranges.
However, it was determined by CDFC that suppression must also be
measured. The other agencies involved ’n SAL'S did not consider
suppression and all recommended that the then f 0 1* Ml 4 he retained.

CDEC, nov/ever, on the basis of the superior rupprosi ive fire and
sustainability characteristics of the M16 recc ■ , i.-nded it bo adopted
and the M14 discontinued. DA reviewed all of the SAWS reports and
recommendations , accepted CDFC's, rejected the others, and the M16 *
became the new US Army rifle. In this case, (.UFO's research con¬
sisted primarily nf setting up acoustic miss distance indicators at
the center of real i stical ly deployed and camoufl agin targets in six
different tactical situations. Squads of troops equipped with
different small arms s vs toms attacked or defend. ui .njainst these
operational arrays. The data was collected by computer and later
Incorporated Into a simplistic mvdel which gave c uppi e. sivo capabil¬
ities Of the weapons one-third of the total ef fi-j. ti veness weight. It
was found in tho field tests that soldiers consistently were able to
put significantly more HI 6 rounds within giver: distances of the target
per unit of tine and per equivalent weight basic lead than wore Ml 4
filers, even at longer ranges.

S'lfMMY

lod.y, w have .) I • • h:|.! <■'! to detail tin- nr. < .«* r. r. i tv of considering
supprrv.. i vf- tin diiii-.n lari', tie. in v/e.jpmr, r,v«. tf-n dr-sign and
evaluation. Hr have mii i-..ir i /nd previous rc.r.irch in the area and
have discussed contributions of past suppression research and have
looked at attempts to model suppression.

Suppression research is a complex area of study requiring multidis¬
ciplinary talents to include primarily those of the soldier and the
psychologist. A considerable body of literature relating to the
subject is currently available, however, some of the most pressing
questions in the area have not been answered. Indeed, some experi¬
enced suppression researchers maintain that some of these question:
may be unanswerable.

51 1

#«' AtH .J -HS

RECAPITULATION

Ac * recult of the cympoelun the ground work was laid for a coherent
approach to achieving c unified method for ctudying auppreecion. After
a thorough review of rhla report, an action plan will be vrltten to follow
through on the ldaac generated during the work eeeelone.

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Full text of "DTIC ADA081134: The Fort Sill Fire Suppression Symposium Report, 24-25 July 1979"

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